Patent Publication Number: US-10310228-B2

Title: Optical lens, image capturing device and electronic device

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 14/800,927, filed on Jul. 16, 2015, now U.S. Pat. No. 9,791,670, which claims priority to Taiwan Application Serial Number 104110961, filed on Apr. 2, 2015, the entirety of which is incorporated by reference herein. 
    
    
     BACKGROUND 
     Technical Field 
     The present disclosure relates to an optical lens and an image capturing device. More particularly, the present disclosure relates to a compact optical lens and image capturing device applicable to electronic devices. 
     Description of Related Art 
     In recent years, with the popularity of mobile terminals having camera functionalities, the demand of miniaturized optical systems has been increasing. The sensor of a conventional optical system is typically a CCD (Charge-Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor) sensor. As the advanced semiconductor manufacturing technologies have allowed the pixel size of sensors to be reduced and compact optical systems have gradually evolved toward the field of higher megapixels, there is an increasing demand for compact optical systems featuring better image quality. 
     A conventional optical system employed in a portable electronic product mainly adopts a four-element lens structure or a five-element lens structure. Due to the popularity of mobile terminals with high-end specifications, such as smart phones, tablet personal computers and wearable apparatus, the requirements for high resolution and image quality of present compact optical systems increase significantly. However, the conventional optical systems cannot satisfy these requirements of the compact optical systems. 
     Other conventional compact optical systems with six-element lens structure enhance image quality and resolution. However, the arrangement of the lens elements thereof cannot provide both of the characteristics of the wide field of view and the compact size for obtain the proper aberration and relative illumination, thus the image quality thereof cannot be improved. 
     SUMMARY 
     According to one aspect of the present disclosure, an optical lens includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. The first lens element with negative refractive power has an image-side surface being concave in a paraxial region thereof. The second lens element has refractive power. The third lens element has positive refractive power. The fourth lens element with positive refractive power has an image-side surface being convex in a paraxial region thereof, wherein an object-side surface and the image-side surface of the fourth lens element are aspheric. The fifth lens element with negative refractive power has an image-side surface being concave in a paraxial region thereof, wherein the image-side surface of the fifth lens element includes at least one convex shape in an off-axis region thereof, and an object-side surface and the image-side surface of the fifth lens element are aspheric. The sixth lens element with refractive power has an image-side surface being concave in a paraxial region thereof, wherein the image-side surface of the sixth lens element includes at least one convex shape in an off-axis region thereof, and an object-side surface and the image-side surface of the sixth lens element are aspheric. The optical lens has a total of six lens elements with refractive power, there is an air space between every two lens elements of the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element and the sixth lens element that are adjacent to each other. When a focal length of the first lens element is f1, a focal length of the second lens element is f2, an axial distance between the first lens element and the second lens element is T12, and an axial distance between the second lens element and the third lens element is T23, the following conditions are satisfied:
 
-0.20&lt;| f 1|/ f 2&lt;1.50; and
 
1.0&lt; T 12/ T 23.
 
     According to another aspect of the present disclosure, an image capturing device includes the optical lens according to the aforementioned aspect and an image sensor, wherein the image sensor is disposed on an image surface of the optical lens. 
     According to further another aspect of the present disclosure, an electronic device includes the image capturing device according to the aforementioned aspect. 
     According to yet another aspect of the present disclosure, an optical lens includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. The first lens element with negative refractive power has an image-side surface being concave in a paraxial region thereof. The second lens element has refractive power. The third lens element has positive refractive power. The fourth lens element with positive refractive power has an image-side surface being convex in a paraxial region thereof, wherein an object-side surface and the image-side surface of the fourth lens element are aspheric. The fifth lens element with negative refractive power has an image-side surface being concave in a paraxial region thereof, wherein an object-side surface and the image-side surface of the fifth lens element are aspheric. The sixth lens element with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof, wherein the image-side surface of the sixth lens element includes at least one convex shape in an off-axis region thereof, and the object-side surface and the image-side surface of the sixth lens element are aspheric. The optical lens has a total of six lens elements with refractive power, there is an air space between every two lens elements of the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element and the sixth lens element that are adjacent to each other. When a focal length of the first lens element is f1, a focal length of the second lens element is f2, a focal length of the fourth lens element is f4, and a focal length of the sixth lens element is f6, the following conditions are satisfied:
 
−1.50&lt;| f 1|/ f 2&lt;4.0; and
 
0&lt; f 6/ f 4&lt;4.0.
 
     According to still another aspect of the present disclosure, an image capturing device includes the optical lens according to the aforementioned aspect and an image sensor, wherein the image sensor is disposed on an image surface of the optical lens. 
     According to further another aspect of the present disclosure, an electronic device includes the image capturing device according to the aforementioned aspect. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of an image capturing device according to the 1st embodiment of the present disclosure; 
         FIG. 2  shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing device according to the 1st embodiment; 
         FIG. 3  is a schematic view of an image capturing device according to the 2nd embodiment of the present disclosure; 
         FIG. 4  shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing device according to the 2nd embodiment; 
         FIG. 5  is a schematic view of an image capturing device according to the 3rd embodiment of the present disclosure; 
         FIG. 6  shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing device according to the 3rd embodiment; 
         FIG. 7  is a schematic view of an image capturing device according to the 4th embodiment of the present disclosure; 
         FIG. 8  shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing device according to the 4th embodiment; 
         FIG. 9  is a schematic view of an image capturing device according to the 5th embodiment of the present disclosure; 
         FIG. 10  shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing device according to the 5th embodiment; 
         FIG. 11  is a schematic view of an image capturing device according to the 6th embodiment of the present disclosure; 
         FIG. 12  shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing device according to the 6th embodiment; 
         FIG. 13  is a schematic view of an image capturing device according to the 7th embodiment of the present disclosure; 
         FIG. 14  shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing device according to the 7th embodiment; 
         FIG. 15  shows a schematic view of the parameter Sag52 according to the 1st embodiment of  FIG. 1 ; 
         FIG. 16  is a schematic view of an electronic device according to the 8th embodiment of the present disclosure; 
         FIG. 17  is a schematic view of an electronic device according to the 9th embodiment of the present disclosure; and 
         FIG. 18  is a schematic view of an electronic device  30  according to the 10th embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     An optical lens includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element, wherein the optical lens has a total of six lens elements with refractive power. 
     There is an air space between every two lens elements of the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element and the sixth lens element that are adjacent to each other. That is, each of the first through sixth lens elements is a single and non-cemented lens element, and every two lens elements adjacent to each other are not cemented. Moreover, the manufacturing process of the cemented lenses is more complex than the non-cemented lenses. In other words, of the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element and the sixth lens element of the optical lens, there is a space in a paraxial region between every pair of lens elements that are adjacent to each other. In particular, a second surface of one lens element and a first surface of the following lens element need to have accurate curvature to ensure these two lens elements will be highly cemented. However, during the cementing process, those two lens elements might not be highly cemented due to displacement and it is thereby not favorable for the image quality of the optical lens. Therefore, according to the optical lens of the present disclosure, an air space in a paraxial region between every two of the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element and the sixth lens element that are adjacent to each other of the present disclosure improves the problem generated by the cemented lens elements. 
     The first lens element with negative refractive power has an image-side surface being concave in a paraxial region thereof. Therefore, the field of view can be increased effectively so as to enlarge the range captured by the optical lens. 
     The second lens element can have positive refractive power, and can have an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. Therefore, the astigmatism of the optical lens can be corrected for enhancing the image quality, and the total track length of the optical lens can be reduced. 
     The third lens element can have positive refractive power, so that the total track length of the optical lens can be further reduced so as to maintain the compact size thereof. 
     The fourth lens element with positive refractive power can have an object-side surface being convex in a paraxial region thereof and including at least one concave shape in an off-axis region thereof, and has an image-side surface being convex in a paraxial region thereof. Therefore, the sensitivity of refractive power distribution of the optical lens can be reduced, and the incident angle of the off-axis field onto the image sensor can be reduced so as to increase the response efficiency of the image sensor. 
     The fifth lens element with negative refractive power has an image-side surface being concave in a paraxial region thereof, wherein the image-side surface of the fifth lens element can include at least one convex shape in an off-axis region thereof. Therefore, the aberration in a paraxial region and an off-axis region of the optical lens can be corrected for enhancing the image quality. 
     The sixth lens element can have positive refractive power and an object-side surface being convex in a paraxial region thereof, and has an image-side surface being concave in a paraxial region thereof and including at least one convex shape in an off-axis region thereof. Therefore, the principal point can be positioned away from the image surface of the optical lens so as to reduce the back focal length for keeping a compact size. Further, it is also favorable for correcting the aberration of the off-axis region so as to enhance the image quality. 
     When a focal length of the first lens element is f1, and a focal length of the second lens element is f2, the following condition is satisfied: −1.50&lt;|f1|/f2&lt;4.0. Therefore, it is favorable for reducing the sensitivity of the surface accuracy of the first lens element and the second lens element by properly adjusting the distribution of the refractive power of the first lens element and the second lens element, and it is also favorable for manufacturing the optical lens by enlarging the field of view. Preferably, the following condition can be satisfied: −0.70&lt;|f1|/f2&lt;1.80. More preferably, the following condition can be satisfied: −0.20&lt;|f1|/f2&lt;1.50. Further preferably, the following condition can be satisfied: −0.20&lt;|f1|/f2&lt;1.0. 
     When an axial distance between the first lens element and the second lens element is T12, and an axial distance between the second lens element and the third lens element is T23, the following condition is satisfied: 1.0&lt;T12/T23. Therefore, the sufficient space between the first lens element and the second lens element can be provided so as to avoid the collision between the first lens element and the second lens element or the second lens element and the third lens element during assembling, and the wide field of view and compact size of the optical lens can be also achieved while providing high image quality thereof. Preferably, the following condition can be satisfied: 1.40&lt;T12/T23. 
     When a focal length of the fourth lens element is f4, and a focal length of the sixth lens element is f6, the following condition is satisfied: 0&lt;f6/f4&lt;4.0. Therefore, the total track length of the optical lens can be reduced so as to maintain the compact size thereof. 
     When half of the maximal field of view of the optical lens is HFOV, and an axial distance between an object-side surface of the first lens element and the image surface is TL, the following conditions are satisfied: 1.30&lt;tan(HFOV); and TL/sin(HFOV×1.6)&lt;7.0 mm. Therefore, the characteristics of large field of view and short total track length of the optical lens can be provided so as to maintain the compact size thereof. 
     When the axial distance between the first lens element and the second lens element is T12, an axial distance between the third lens element and the fourth lens element is T34, an axial distance between the fourth lens element and the fifth lens element is T45, and an axial distance between the fifth lens element and the sixth lens element is T56, the following condition is satisfied: 1.25&lt;T12/(T34+T45+T56)&lt;4.0. Therefore, the lens elements between the stop and the image surface can be arranged closely, and the additional element, such as a spacer which is disposed between two lens elements with excessive distance can be omitted. 
     When a central thickness of the first lens element is CT1, a central thickness of the second lens element is CT2, a central thickness of the third lens element is CT3, a central thickness of the fourth lens element is CT4, and a central thickness of the sixth lens element is CT6, the following conditions are satisfied: CT1&lt;CT2; CT1&lt;CT3; CT1&lt;CT4; and CT1&lt;CT6. Therefore, it is favorable for the manufacturing and assembling of the lens elements so as to obtain the high image quality. 
     When a focal length of the optical lens is f, and a curvature radius of the object-side surface of the sixth lens element is R11, the following condition is to satisfied: 0&lt;R11/f&lt;1.40. Therefore, it is favorable for obtaining high image quality by correcting the aberration generated from the fifth lens element. Preferably, the following condition can be satisfied: 0&lt;R11/f&lt;1.0. 
     When a central thickness of the fifth lens element is CT5, and a distance in parallel with an optical axis from an axial vertex on the image-side surface of the fifth lens element to a maximum effective diameter position on the image-side surface of the fifth lens element is Sag52 (Sag52 is a positive value with the distance in parallel with the optical axis towards the image side; Sag52 is a negative value with the distance in parallel with the optical axis towards the object side), and the following condition is satisfied: 4.0&lt;CT5/|Sag52|. Therefore, the shape of the lens element is proper for manufacturing and forming thereof, and the defective forming can be reduced. 
     When a refractive index of the first lens element is N1, a refractive index of the second lens element is N2, a refractive index of the third lens element is N3, a refractive index of the fourth lens element is N4, a refractive index of the fifth lens element is N5, a refractive index of the sixth lens element is N6, and a maximum of N1, N2, N3, N4, N5 and N6 is Nmax, the following condition is satisfied: 1.60&lt;Nmax&lt;1.70. Therefore, it is favorable for reducing the aberration by the proper material of the lens elements. 
     When the focal length of the first lens element is f1, the focal length of the second lens element is f2, a focal length of the third lens element is f3, the focal length of the fourth lens element is f4, a focal length of the fifth lens element is f5, and the focal length of the sixth lens element is f6, the following conditions are satisfied: |f5|&lt;|f1|; |f5|&lt;|f2|; |f5|&lt;|f3|; |f5|&lt;|f4|; and |f5|&lt;|f6|. Therefore, it is favorable for correcting the aberration by the proper distribution of the refractive power of the optical lens. 
     According to the optical lens of the present disclosure, the lens elements thereof can be made of glass or plastic material. When the lens elements are made of glass material, the distribution of the refractive powers of the optical lens may be more flexible to design. When the lens elements are made of plastic material, the manufacturing cost can be effectively reduced. Furthermore, surfaces of each lens element can be arranged to be aspheric, since the aspheric surface of the lens element is easy to form a shape other than spherical surface so as to have more controllable variables for eliminating the aberration thereof, and to further decrease the required number of the lens elements. Therefore, the total track length of the optical lens can also be reduced. 
     According to the optical lens of the present disclosure, each of an object-side surface and an image-side surface has a paraxial region and an off-axis region. The paraxial region refers to the region of the surface where light rays travel close to the optical axis, and the off-axis region refers to the region of the surface away from the paraxial region. Particularly, when the lens element has a convex surface, it indicates that the surface is convex in the paraxial region thereof; when the lens element has a concave surface, it indicates that the surface is concave in the paraxial region thereof. 
     According to the optical lens of the present disclosure, the positive refractive power or the negative refractive power of a lens element or the focal length of the lens element, that is, refers to the refractive power or the focal length in a paraxial region of the lens element. 
     According to the optical lens of the present disclosure, the optical lens can include at least one stop, such as an aperture stop, a glare stop or a field stop. Said glare stop or said field stop is for eliminating the stray light and thereby improving the image resolution thereof. 
     According to the optical lens of the present disclosure, an image surface of the optical lens, based on the corresponding image sensor, can be flat or curved. In particular, the image surface can be a curved surface being concave facing towards the object side. 
     According to the optical lens of the present disclosure, an aperture stop can be configured as a front stop or a middle stop. A front stop disposed between an object and the first lens element can provide a longer distance between an exit pupil of the optical lens and the image surface and thereby improves the image-sensing efficiency of an image sensor. A middle stop disposed between the first lens element and the image surface is favorable for enlarging the field of view of the optical lens and thereby provides a wider field of view for the same. 
     According to the optical lens of the present disclosure, the optical lens can be applied to 3D (three-dimensional) image capturing applications, in products such as digital cameras, mobile devices, digital tablets, smart TV, internet monitoring device, motion sensing input device, vehicle device (such as driving recording systems, vehicle reversing displays), rear view camera systems, and wearable devices. 
     According to the present disclosure, an image capturing device is provided. The image capturing device includes the aforementioned optical lens and an image sensor, wherein the image sensor is disposed on the image side of the aforementioned optical lens, that is, the image sensor can be disposed on or near an image surface of the aforementioned optical lens. In the image capturing device with the arrangement of the aforementioned optical lens, the wide field of view and the compact size thereof can be obtained with the proper distribution of the aberration and relative illumination, and the proper arrangement of the shape of the lens element can be obtained easily. Preferably, the image capturing device can further include a barrel member, a holding member or a combination thereof. 
     According to the present disclosure, an electronic device is provided. The electronic device includes the aforementioned image capturing device. Therefore, the image quality of the electronic device can be increased. Preferably, the electronic device can further include but not limited to a control unit, a display, a storage unit, a random access memory unit (RAM), a read only memory unit (ROM) or a combination thereof. 
     According to the above description of the present disclosure, the following 1st-10th specific embodiments are provided for further explanation. 
     1st Embodiment 
       FIG. 1  is a schematic view of an image capturing device according to the 1st embodiment of the present disclosure.  FIG. 2  shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing device according to the 1st embodiment. In  FIG. 1 , the image capturing device includes an optical lens (its reference numeral is omitted) and an image sensor  190 . The optical lens includes, in order from an object side to an image side, a first lens element  110 , a second lens element  120 , an aperture stop  100 , a third lens element  130 , a fourth lens element  140 , a fifth lens element  150 , a sixth lens element  160 , an IR-cut filter  170  and an image surface  180 , wherein the image sensor  190  is disposed on the image surface  180  of the optical lens. The optical lens has a total of sixth lens elements ( 110 - 160 ) with refractive power, and there is an air space between every two lens elements of the first lens element  110 , the second lens element  120 , the third lens element  130 , the fourth lens element  140 , the fifth lens element  150  and the sixth lens element  160  that are adjacent to each other. 
     The first lens element  110  with negative refractive power has an object-side surface  111  being convex in a paraxial region thereof and an image-side surface  112  being concave in a paraxial region thereof. The first lens element  110  is made of plastic material, and has the object-side surface  111  and the image-side surface  112  being both aspheric. 
     The second lens element  120  with negative refractive power has an object-side surface  121  being convex in a paraxial region thereof and an image-side surface  122  being concave in a paraxial region thereof. The second lens element  120  is made of plastic material, and has the object-side surface  121  and the image-side surface  122  being both aspheric. 
     The third lens element  130  with positive refractive power has an object-side surface  131  being convex in a paraxial region thereof and an image-side surface  132  being convex in a paraxial region thereof. The third lens element  130  is made of plastic material, and has the object-side surface  131  and the image-side surface  132  being both aspheric. 
     The fourth lens element  140  with positive refractive power has an object-side surface  141  being convex in a paraxial region thereof, and an image-side surface  142  being convex in a paraxial region thereof and including at least one concave shape in an off-axis region thereof. The fourth lens element  140  is made of plastic material, and has the object-side surface  141  and the image-side surface  142  being both aspheric. 
     The fifth lens element  150  with negative refractive power has an object-side surface  151  being concave in a paraxial region thereof, and an image-side surface  152  being concave in a paraxial region thereof and including at least one convex shape in an off-axis region thereof. The fifth lens element  150  is made of plastic material, and has the object-side surface  151  and the image-side surface  152  being both aspheric. 
     The sixth lens element  160  with positive refractive power has an object-side surface  161  being convex in a paraxial region thereof, and an image-side surface  162  being concave in a paraxial region thereof and including at least one convex shape in an off-axis region thereof. The sixth lens element  160  is made of plastic material, and has the object-side surface  161  and the image-side surface  162  being both aspheric. 
     The IR-cut filter  170  is made of glass material and located between the sixth lens element  160  and the image surface  180 , and will not affect a focal length of the optical lens. 
     The equation of the aspheric surface profiles of the aforementioned lens elements of the 1st embodiment is expressed as follows: 
                 X   ⁡     (   Y   )       =         (       Y   2     /   R     )     /     (     1   +     sqrt   ⁡     (     1   -       (     1   +   k     )     ×       (     Y   /   R     )     2         )         )       +       ∑   i     ⁢           ⁢       (   Ai   )     ×     (     Y   i     )             ,         
where,
 
     X is the relative distance between a point on the aspheric surface spaced at a distance Y from the optical axis and the tangential plane at the aspheric surface vertex on the optical axis; 
     Y is the vertical distance from the point on the aspheric surface to the optical axis; 
     R is the curvature radius; 
     k is the conic coefficient; and 
     Ai is the i-th aspheric coefficient. 
     In the optical lens according to the 1st embodiment, when a focal length of the optical lens is f, an f-number of the optical lens is Fno, and half of a maximal field of view of the optical lens is HFOV, these parameters have the following values: f=1.00 mm; Fno=2.15; and HFOV=63.5 degrees. 
     In the optical lens according to the 1st embodiment, when half of the maximal field of view of the optical lens is HFOV, the following condition is satisfied: tan(HFOV)=2.01. 
     In the optical lens according to the 1st embodiment, when a refractive index of the first lens element  110  is N1, a refractive index of the second lens element  120  is N2, a refractive index of the third lens element  130  is N3, a refractive index of the fourth lens element  140  is N4, a refractive index of the fifth lens element  150  is N5, a refractive index of the sixth lens element  160  is N6, and a maximum of N1, N2, N3, N4, N5 and N6 is Nmax, the following condition is satisfied: Nmax=1.633. 
     In the optical lens according to the 1st embodiment, when an axial distance between the first lens element  110  and the second lens element  120  is T12, an axial distance between the second lens element  120  and the third lens element  130  is T23, an axial distance between the third lens element  130  and the fourth lens element  140  is T34, an axial distance between the fourth lens element  140  and the fifth lens element  150  is T45, and an axial distance between the fifth lens element  150  and the sixth lens element  160  is T56, the following conditions are satisfied: T12/T23=1.85; and T12/(T34+T45+T56)=1.51. 
     In the optical lens according to the 1st embodiment, when half of the maximal field of view of the optical lens is HFOV, and an axial distance between the object-side surface  111  of the first lens element  110  and the image surface  180  is TL, the following condition is satisfied: TL/sin(HFOV×1.6)=4.30 mm. 
       FIG. 15  shows a schematic view of the parameter Sag52 according to the 1st embodiment of  FIG. 1 . In  FIG. 15 , when a distance in parallel with an optical axis from an axial vertex on the image-side surface  152  of the fifth lens element  150  to a maximum effective diameter position on the image-side surface  152  of the fifth lens element  150  is Sag52, and a central thickness of the fifth lens element  150  is CT5, the following condition is satisfied: CT5/|Sag52|=7.18. 
     In the optical lens according to the 1st embodiment, when the focal length of the optical lens is f, and a curvature radius of the object-side surface  161  of the sixth lens element  160  is R11, the following condition is satisfied: R11/f=0.56. 
     In the optical lens according to the 1st embodiment, when a focal length of the first lens element  110  is f1, and a focal length of the second lens element  120  is f2, the following condition is satisfied: |f1|/f2=−0.04. 
     In the optical lens according to the 1st embodiment, when a focal length of the fourth lens element  140  is f4, and a focal length of the sixth lens element  160  is f6, the following condition is satisfied: f6/f4=1.06. 
     In the optical lens according to the 1st embodiment, when a central thickness of the first lens element  110  is CT1, a central thickness of the second lens element  120  is CT2, a central thickness of the third lens element  130  is CT3, a central thickness of the fourth lens element  140  is CT4, and a central thickness of the sixth lens element  160  is CT6, the following conditions are satisfied: CT1&lt;CT2; CT1&lt;CT3; CT1&lt;CT4; and CT1&lt;CT6. 
     In the optical lens according to the 1st embodiment, when the focal length of the first lens element  110  is f1, the focal length of the second lens element  120  is f2, a focal length of the third lens element  130  is f3, the focal length of the fourth lens element  140  is f4, a focal length of the fifth lens element  150  is f5, and the focal length of the sixth lens element  160  is f, the following conditions are satisfied: |f5|&lt;|f1|; |f5|&lt;|f2|; |f5|&lt;|f3|; |f5|&lt;|f4|; and |f5|&lt;|f6|. 
     The detailed optical data of the 1st embodiment are shown in Table 1 and the aspheric surface data are shown in Table 2 below. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 1st Embodiment 
               
               
                 f = 1.00 mm, Fno = 2.15, HFOV = 63.5 deg. 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Curvature 
                   
                   
                   
                   
                 Focal 
               
               
                 Surface # 
                   
                 Radius 
                 Thickness 
                 Material 
                 Index 
                 Abbe # 
                 Length 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 0 
                 Object 
                 Plano 
                 Infinity 
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 1 
                 Lens 1 
                 2.018 
                 ASP 
                 0.255 
                 Plastic 
                 1.544 
                 55.9 
                 −1.49 
               
               
                 2 
                   
                 0.553 
                 ASP 
                 0.425 
               
               
                 3 
                 Lens 2 
                 0.995 
                 ASP 
                 0.300 
                 Plastic 
                 1.633 
                 23.4 
                 −33.50 
               
               
                 4 
                   
                 0.840 
                 ASP 
                 0.256 
               
            
           
           
               
               
               
               
               
            
               
                 5 
                 Ape. Stop 
                 Plano 
                 −0.026 
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 6 
                 Lens 3 
                 2.263 
                 ASP 
                 0.472 
                 Plastic 
                 1.514 
                 56.8 
                 1.59 
               
               
                 7 
                   
                 −1.188 
                 ASP 
                 0.104 
               
               
                 8 
                 Lens 4 
                 2.440 
                 ASP 
                 0.640 
                 Plastic 
                 1.644 
                 55.9 
                 0.98 
               
               
                 9 
                   
                 −0.623 
                 ASP 
                 0.095 
               
               
                 10 
                 Lens 5 
                 −0.645 
                 ASP 
                 0.255 
                 Plastic 
                 1.633 
                 23.4 
                 −0.62 
               
               
                 11 
                   
                 1.166 
                 ASP 
                 0.082 
               
               
                 12 
                 Lens 6 
                 0.564 
                 ASP 
                 0.636 
                 Plastic 
                 1.544 
                 55.9 
                 1.04 
               
               
                 13 
                   
                 83.034 
                 ASP 
                 0.400 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 14 
                 IR-cut filter 
                 Plano 
                 0.110 
                 Glass 
                 1.517 
                 64.2 
                 — 
               
               
                 15 
                   
                 Plano 
                 0.205 
               
               
                 16 
                 Image 
                 Plano 
                 — 
               
               
                   
               
               
                 Note: 
               
               
                 Reference wavelength is 587.6 nm (d-line). 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Aspheric Coefficients 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                   
                 Surface # 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 1 
                 2 
                 3 
                 4 
                 6 
                 7 
               
               
                   
               
               
                 k = 
                 −4.9227E−02 
                 −7.3854E−01 
                 2.4401E−01 
                 −2.6108E+00 
                 8.8144E+00 
                 −3.0299E+00 
               
               
                 A4 = 
                 3.1658E−01 
                 4.4670E−01 
                 −1.1812E−02 
                 1.5348E+00 
                 2.4989E−02 
                 −1.2630E+00 
               
               
                 A6 = 
                 −8.1019E−01 
                 −2.2742E−01 
                 1.2351E+00 
                 4.4101E+00 
                 −5.5532E−01 
                 2.0216E+00 
               
               
                 A8 = 
                 7.8938E−01 
                 −1.1679E+01 
                 −1.6029E+01 
                 −4.4695E+01 
                 6.8535E+00 
                 −1.0459E+01 
               
               
                 A10 = 
                 −3.5874E−01 
                 2.8169E+01 
                 5.9385E+01 
                 4.7020E+02 
                 −1.9666E+01 
                 2.0715E+01 
               
               
                 A12 = 
                 6.3971E−02 
                 −1.8875E+01 
                 −7.2674E+01 
                 −9.6417E+02 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 Surface # 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 8 
                 9 
                 10 
                 11 
                 12 
                 13 
               
               
                   
               
               
                 k = 
                 3.9565E−01 
                 −8.9787E−01 
                 −8.4168E−01 
                 −3.6612E+01 
                 −6.5044E+00 
                 3.0359E+01 
               
               
                 A4 = 
                 −5.3590E−01 
                 2.7958E+00 
                 3.7728E+00 
                 −8.3013E−02 
                 −7.6512E−02 
                 3.6772E−01 
               
               
                 A6 = 
                 7.9918E−01 
                 −1.6443E+01 
                 −2.4033E+01 
                 −3.6156E−01 
                 2.9110E−01 
                 −4.8043E−01 
               
               
                 A8 = 
                 −1.4788E+00 
                 4.8331E+01 
                 7.6076E+01 
                 7.2435E−01 
                 −7.4546E−01 
                 2.2581E−01 
               
               
                 A10 = 
                 −3.2925E+00 
                 −7.5388E+01 
                 −1.5158E+02 
                 −6.6294E−01 
                 7.8278E−01 
                 −4.5073E−02 
               
               
                 A12 = 
                   
                 4.7744E+01 
                 1.7735E+02 
                 3.9845E−01 
                 −3.8651E−01 
                 2.1856E−02 
               
               
                 A14 = 
                   
                   
                 −8.7128E+01 
                 −1.1724E−01 
                 7.3004E−02 
                 −1.6020E−02 
               
               
                 A16 = 
                   
                   
                   
                   
                   
                 3.3656E−03 
               
               
                   
               
            
           
         
       
     
     In Table 1, the curvature radius, the thickness and the focal length are shown in millimeters (mm). Surface numbers 0-16 represent the surfaces sequentially arranged from the object-side to the image-side along the optical axis. In Table 2, k represents the conic coefficient of the equation of the aspheric surface profiles. A4-A16 represent the aspheric coefficients ranging from the 4th order to the 16th order. The tables presented below for each embodiment are the corresponding schematic parameter and aberration curves, and the definitions of the tables are the same as Table 1 and Table 2 of the 1st embodiment. Therefore, an explanation in this regard will not be provided again. 
     2nd Embodiment 
       FIG. 3  is a schematic view of an image capturing device according to the 2nd embodiment of the present disclosure.  FIG. 4  shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing device according to the 2nd embodiment. In  FIG. 3 , the image capturing device includes an optical lens (its reference numeral is omitted) and an image sensor  290 . The optical lens includes, in order from an object side to an image side, a first lens element  210 , a second lens element  220 , an aperture stop  200 , a third lens element  230 , a fourth lens element  240 , a fifth lens element  250 , a sixth lens element  260 , an IR-cut filter  270  and an image surface  280 , wherein the image sensor  290  is disposed on the image surface  280  of the optical lens. The optical lens has a total of sixth lens elements ( 210 - 260 ) with refractive power, and there is an air space between every two lens elements of the first lens element  210 , the second lens element  220 , the third lens element  230 , the fourth lens element  240 , the fifth lens element  250  and the sixth lens element  260  that are adjacent to each other. 
     The first lens element  210  with negative refractive power has an object-side surface  211  being convex in a paraxial region thereof and an image-side surface  212  being concave in a paraxial region thereof. The first lens element  210  is made of plastic material, and has the object-side surface  211  and the image-side surface  212  being both aspheric. 
     The second lens element  220  with positive refractive power has an object-side surface  221  being convex in a paraxial region thereof and an image-side surface  222  being concave in a paraxial region thereof. The second lens element  220  is made of plastic material, and has the object-side surface  221  and the image-side surface  222  being both aspheric. 
     The third lens element  230  with positive refractive power has an object-side surface  231  being convex in a paraxial region thereof and an image-side surface  232  being convex in a paraxial region thereof. The third lens element  230  is made of plastic material, and has the object-side surface  231  and the image-side surface  232  being both aspheric. 
     The fourth lens element  240  with positive refractive power has an object-side surface  241  being concave in a paraxial region thereof, and an image-side surface  242  being convex in a paraxial region thereof and including at least one concave shape in an off-axis region thereof. The fourth lens element  240  is made of plastic material, and has the object-side surface  241  and the image-side surface  242  being both aspheric. 
     The fifth lens element  250  with negative refractive power has an object-side surface  251  being concave in a paraxial region thereof, and an image-side surface  252  being concave in a paraxial region thereof and including at least one convex shape in an off-axis region thereof. The fifth lens element  250  is made of plastic material, and has the object-side surface  251  and the image-side surface  252  being both aspheric. 
     The sixth lens element  260  with positive refractive power has an object-side surface  261  being convex in a paraxial region thereof, and an image-side surface  262  being concave in a paraxial region thereof and including at least one convex shape in an off-axis region thereof. The sixth lens element  260  is made of plastic material, and has the object-side surface  261  and the image-side surface  262  being both aspheric. 
     The IR-cut filter  270  is made of glass material and located between the sixth lens element  260  and the image surface  280 , and will not affect a focal length of the optical lens. 
     The detailed optical data of the 2nd embodiment are shown in Table 3 and the aspheric surface data are shown in Table 4 below. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 2nd Embodiment 
               
               
                 f = 1.23 mm, Fno = 2.38, HFOV = 59.5 deg. 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Curvature 
                   
                   
                   
                   
                 Focal 
               
               
                 Surface # 
                   
                 Radius 
                 Thickness 
                 Material 
                 Index 
                 Abbe # 
                 Length 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 0 
                 Object 
                 Plano 
                 Infinity 
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 1 
                 Lens 1 
                 2.156 
                 ASP 
                 0.316 
                 Plastic 
                 1.544 
                 55.9 
                 −1.77 
               
               
                 2 
                   
                 0.632 
                 ASP 
                 0.487 
               
               
                 3 
                 Lens 2 
                 1.073 
                 ASP 
                 0.403 
                 Plastic 
                 1.645 
                 22.5 
                 18.26 
               
               
                 4 
                   
                 1.007 
                 ASP 
                 0.271 
               
            
           
           
               
               
               
               
               
            
               
                 5 
                 Ape. Stop 
                 Plano 
                 −0.008 
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 6 
                 Lens 3 
                 4.609 
                 ASP 
                 0.495 
                 Plastic 
                 1.535 
                 55.7 
                 1.49 
               
               
                 7 
                   
                 −0.930 
                 ASP 
                 0.093 
               
               
                 8 
                 Lens 4 
                 −13.833 
                 ASP 
                 0.697 
                 Plastic 
                 1.535 
                 55.7 
                 2.10 
               
               
                 9 
                   
                 −1.059 
                 ASP 
                 0.076 
               
               
                 10 
                 Lens 5 
                 −1.344 
                 ASP 
                 0.270 
                 Plastic 
                 1.645 
                 22.5 
                 −1.01 
               
               
                 11 
                   
                 1.351 
                 ASP 
                 0.040 
               
               
                 12 
                 Lens 6 
                 0.638 
                 ASP 
                 0.800 
                 Plastic 
                 1.544 
                 55.9 
                 1.22 
               
               
                 13 
                   
                 8.813 
                 ASP 
                 0.419 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 14 
                 IR-cut filter 
                 Plano 
                 0.210 
                 Glass 
                 1.517 
                 64.2 
                 — 
               
               
                 15 
                   
                 Plano 
                 0.285 
               
               
                 16 
                 Image 
                 Plano 
                 — 
               
               
                   
               
               
                 Note: 
               
               
                 Reference wavelength is 587.6 nm (d-line). 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 4 
               
               
                   
               
               
                 Aspheric Coefficients 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                   
                 Surface # 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 1 
                 2 
                 3 
                 4 
                 6 
                 7 
               
               
                   
               
               
                 k = 
                 −6.2694E−02 
                 −7.7175E−01 
                 1.0203E−01 
                 −1.8197E+00 
                 7.3347E+01 
                 −5.9589E+00 
               
               
                 A4 = 
                 1.7715E−01 
                 3.7902E−01 
                 −4.4158E−02 
                 1.0408E+00 
                 4.4296E−01 
                 −9.4897E−01 
               
               
                 A6 = 
                 −3.2289E−01 
                 −8.7987E−01 
                 1.4120E+00 
                 −1.4223E+00 
                 −1.5785E+01 
                 7.7901E+00 
               
               
                 A8 = 
                 2.2767E−01 
                 9.4688E−01 
                 −8.3321E+00 
                 1.0142E+02 
                 3.7328E+02 
                 −9.8073E+01 
               
               
                 A10 = 
                 −8.9832E−02 
                 −5.3241E+00 
                 2.7021E+01 
                 −1.2939E+03 
                 −4.9099E+03 
                 7.0348E+02 
               
               
                 A12 = 
                 2.3859E−02 
                 1.2348E+01 
                 −5.1534E+01 
                 9.2029E+03 
                 3.6855E+04 
                 −2.8651E+03 
               
               
                 A14 = 
                 −4.9108E−03 
                 −1.1195E+01 
                 5.8472E+01 
                 −3.0881E+04 
                 −1.4520E+05 
                 6.1838E+03 
               
               
                 A16 = 
                 6.0765E−04 
                 3.5230E+00 
                 −3.5683E+01 
                 4.0081E+04 
                 2.3223E+05 
                 −5.3510E+03 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 Surface # 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 8 
                 9 
                 10 
                 11 
                 12 
                 13 
               
               
                   
               
               
                 k = 
                 9.0000E+01 
                 −2.1221E−01 
                 9.2211E−01 
                 −4.2143E+01 
                 −8.2127E+00 
                 −4.4046E+00 
               
               
                 A4 = 
                 4.6803E−01 
                 3.7134E−01 
                 4.2203E−01 
                 −7.3321E−01 
                 6.8748E−02 
                 6.6934E−01 
               
               
                 A6 = 
                 −2.1324E+00 
                 −1.1087E+00 
                 −3.6910E−01 
                 2.8509E+00 
                 −9.1382E−01 
                 −1.6533E+00 
               
               
                 A8 = 
                 6.2700E+00 
                 −3.4985E+00 
                 −4.5836E+00 
                 −5.6666E+00 
                 2.2292E+00 
                 1.9444E+00 
               
               
                 A10 = 
                 −1.3252E+01 
                 1.9532E+01 
                 9.2953E+00 
                 5.8564E+00 
                 −2.5713E+00 
                 −1.3127E+00 
               
               
                 A12 = 
                 2.1989E+00 
                 −3.7505E+01 
                 −7.6654E+00 
                 −3.0255E+00 
                 1.4212E+00 
                 5.0231E−01 
               
               
                 A14 = 
                 3.5065E+01 
                 3.2860E+01 
                 6.7683E+00 
                 5.6856E−01 
                 −3.0842E−01 
                 −1.0074E−01 
               
               
                 A16 = 
                 −3.8438E+01 
                 −1.0169E+01 
                 −3.7196E+00 
                 3.4356E−02 
                   
                 8.2114E−03 
               
               
                   
               
            
           
         
       
     
     In the 2nd embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 2nd embodiment, so an explanation in this regard will not be provided again. 
     Moreover, these parameters can be calculated from Table 3 and Table 4 as the following values and satisfy the following conditions: 
     
       
         
           
               
             
               
                   
               
               
                 2nd Embodiment 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 f [mm] 
                 1.23 
                 T12/(T34 + T45 + T56) 
                 2.33 
               
               
                   
                 Fno 
                 2.38 
                 TL/sin(HFOV × 1.6) [mm] 
                 4.87 
               
               
                   
                 HFOV [deg.] 
                 59.5 
                 CT5/|Sag52| 
                 48.68 
               
               
                   
                 tan(HFOV) 
                 1.70 
                 R11/f 
                 0.52 
               
               
                   
                 Nmax 
                 1.645 
                 |f1|/f2 
                 0.10 
               
               
                   
                 T12/T23 
                 1.85 
                 f6/f4 
                 0.58 
               
               
                   
                   
               
            
           
         
       
     
     Furthermore, according to the 2nd embodiment, when a central thickness of the first lens element  210  is CT1, a central thickness of the second lens element  220  is CT2, a central thickness of the third lens element  230  is CT3, a central thickness of the fourth lens element  240  is CT4, and a central thickness of the sixth lens element  260  is CT6, the following conditions are satisfied: CT1&lt;CT2; CT1&lt;CT3; CT1&lt;CT4; and CT1&lt;CT6. 
     According to the 2nd embodiment, when the focal length of the first lens element  210  is f1, the focal length of the second lens element  220  is f2, a focal length of the third lens element  230  is f3, the focal length of the fourth lens element  240  is f4, a focal length of the fifth lens element  250  is f5, and the focal length of the sixth lens element  260  is f6, the following conditions are satisfied: |f5|&lt;|f1|; |f5|&lt;|f2|; |f5|&lt;|f3|; |f5|&lt;|f4|; and |f5|&lt;|f6|. 
     3rd Embodiment 
       FIG. 5  is a schematic view of an image capturing device according to the 3rd embodiment of the present disclosure.  FIG. 6  shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing device according to the 3rd embodiment. In  FIG. 5 , the image capturing device includes an optical lens (its reference numeral is omitted) and an image sensor  390 . The optical lens includes, in order from an object side to an image side, a first lens element  310 , a second lens element  320 , an aperture stop  300 , a third lens element  330 , a fourth lens element  340 , a fifth lens element  350 , a sixth lens element  360 , an IR-cut filter  370  and an image surface  280 , wherein the image sensor  290  is disposed on the image surface  380  of the optical lens. The optical lens has a total of sixth lens elements ( 310 - 360 ) with refractive power, and there is an air space between every two lens elements of the first lens element  310 , the second lens element  320 , the third lens element  330 , the fourth lens element  340 , the fifth lens element  350  and the sixth lens element  360  that are adjacent to each other. 
     The first lens element  310  with negative refractive power has an object-side surface  311  being convex in a paraxial region thereof and an image-side surface  312  being concave in a paraxial region thereof. The first lens element  310  is made of plastic material, and has the object-side surface  311  and the image-side surface  312  being both aspheric. 
     The second lens element  320  with positive refractive power has an object-side surface  321  being convex in a paraxial region thereof and an image-side surface  322  being concave in a paraxial region thereof. The second lens element  320  is made of plastic material, and has the object-side surface  321  and the image-side surface  322  being both aspheric. 
     The third lens element  330  with positive refractive power has an object-side surface  331  being convex in a paraxial region thereof and an image-side surface  332  being convex in a paraxial region thereof. The third lens element  330  is made of plastic material, and has the object-side surface  331  and the image-side surface  332  being both aspheric. 
     The fourth lens element  340  with positive refractive power has an object-side surface  341  being convex in a paraxial region thereof, and an image-side surface  342  being convex in a paraxial region thereof and including at least one concave shape in an off-axis region thereof. The fourth lens element  340  is made of plastic material, and has the object-side surface  341  and the image-side surface  342  being both aspheric. 
     The fifth lens element  350  with negative refractive power has an object-side surface  351  being concave in a paraxial region thereof, and an image-side surface  352  being concave in a paraxial region thereof and including at least one convex shape in an off-axis region thereof. The fifth lens element  350  is made of plastic material, and has the object-side surface  351  and the image-side surface  352  being both aspheric. 
     The sixth lens element  360  with positive refractive power has an object-side surface  361  being convex in a paraxial region thereof, and an image-side surface  362  being concave in a paraxial region thereof and including at least one convex shape in an off-axis region thereof. The sixth lens element  360  is made of plastic material, and has the object-side surface  361  and the image-side surface  362  being both aspheric. 
     The IR-cut filter  370  is made of glass material and located between the sixth lens element  360  and the image surface  380 , and will not affect a focal length of the optical lens. 
     The detailed optical data of the 3rd embodiment are shown in Table 5 and the aspheric surface data are shown in Table 6 below. 
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 3rd Embodiment 
               
               
                 f = 1.22 mm, Fno = 2.29, HFOV = 59.3 deg. 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Curvature 
                   
                   
                   
                   
                 Focal 
               
               
                 Surface # 
                   
                 Radius 
                 Thickness 
                 Material 
                 Index 
                 Abbe # 
                 Length 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 0 
                 Object 
                 Plano 
                 Infinity 
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 1 
                 Lens 1 
                 2.000 
                 ASP 
                 0.240 
                 Plastic 
                 1.544 
                 55.9 
                 −1.77 
               
               
                 2 
                   
                 0.623 
                 ASP 
                 0.558 
               
               
                 3 
                 Lens 2 
                 1.234 
                 ASP 
                 0.401 
                 Plastic 
                 1.639 
                 23.5 
                 6.34 
               
               
                 4 
                   
                 1.550 
                 ASP 
                 0.214 
               
            
           
           
               
               
               
               
               
            
               
                 5 
                 Ape. Stop 
                 Plano 
                 −0.052 
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 6 
                 Lens 3 
                 1.457 
                 ASP 
                 0.359 
                 Plastic 
                 1.544 
                 55.9 
                 2.18 
               
               
                 7 
                   
                 −5.780 
                 ASP 
                 0.037 
               
               
                 8 
                 Lens 4 
                 4.765 
                 ASP 
                 0.532 
                 Plastic 
                 1.544 
                 55.9 
                 1.05 
               
               
                 9 
                   
                 −0.624 
                 ASP 
                 0.052 
               
               
                 10 
                 Lens 5 
                 −1.116 
                 ASP 
                 0.260 
                 Plastic 
                 1.639 
                 23.5 
                 −1.01 
               
               
                 11 
                   
                 1.678 
                 ASP 
                 0.122 
               
               
                 12 
                 Lens 6 
                 0.694 
                 ASP 
                 0.493 
                 Plastic 
                 1.544 
                 55.9 
                 2.31 
               
               
                 13 
                   
                 1.161 
                 ASP 
                 0.400 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 14 
                 IR-cut filter 
                 Plano 
                 0.110 
                 Glass 
                 1.517 
                 64.2 
                 — 
               
               
                 15 
                   
                 Plano 
                 0.266 
               
               
                 16 
                 Image 
                 Plano 
                 — 
               
               
                   
               
               
                 Note: 
               
               
                 Reference wavelength is 587.6 nm (d-line). 
               
               
                 An effective radius of surface 9 is 0.602 mm. 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 6 
               
               
                   
               
               
                 Aspheric Coefficients 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                   
                 Surface # 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 1 
                 2 
                 3 
                 4 
                 6 
                 7 
               
               
                   
               
               
                 k = 
                 6.6510E−01 
                 −7.4191E−01 
                 1.5808E−01 
                 −4.9821E+01 
                 −4.1944E+01 
                 7.7108E+01 
               
               
                 A4 = 
                 4.9732E−02 
                 3.1281E−02 
                 −2.9219E−01 
                 2.1238E+00 
                 1.7435E+00 
                 −1.5372E+00 
               
               
                 A6 = 
                 −1.4418E−01 
                 −3.0106E−01 
                 −6.9012E−02 
                 −1.4986E+01 
                 −7.8759E+00 
                 4.1014E−02 
               
               
                 A8 = 
                 1.2291E−01 
                 −5.5456E−01 
                 −8.8010E−01 
                 1.3307E+02 
                 2.9283E+01 
                 −1.7734E+01 
               
               
                 A10 = 
                 −4.9994E−02 
                 6.6756E−01 
                 3.8858E+00 
                 −5.9453E+02 
                 −3.1698E+01 
                 1.0875E+02 
               
               
                 A12 = 
                 6.9888E−03 
                 −1.4797E−01 
                 −3.4025E+00 
                 1.2908E+03 
                 −1.5926E+02 
                 −2.4371E+02 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 Surface # 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 8 
                 9 
                 10 
                 11 
                 12 
                 13 
               
               
                   
               
               
                 k = 
                 −2.0230E+01 
                 −1.0363E+00 
                 2.7882E−01 
                 −8.9105E+01 
                 −7.6251E+00 
                 −4.9220E−01 
               
               
                 A4 = 
                 −1.4020E+00 
                 3.3735E+00 
                 3.3679E+00 
                 2.4872E−01 
                 −2.2356E−01 
                 −5.8941E−01 
               
               
                 A6 = 
                 1.3879E−01 
                 −3.2539E+01 
                 −3.0602E+01 
                 −2.2698E+00 
                 1.8790E−01 
                 4.7706E−01 
               
               
                 A8 = 
                 −1.9381E+01 
                 1.4231E+02 
                 1.1570E+02 
                 5.6244E+00 
                 3.0428E−02 
                 −3.3868E−01 
               
               
                 A10 = 
                 4.2267E+01 
                 −3.3557E+02 
                 −2.5375E+02 
                 −7.8399E+00 
                 −2.2646E−01 
                 1.5986E−01 
               
               
                 A12 = 
                   
                 3.4845E+02 
                 2.6826E+02 
                 5.8524E+00 
                 1.5386E−01 
                 −5.1300E−02 
               
               
                 A14 = 
                   
                   
                 −6.0171E+01 
                 −1.7946E+00 
                 −3.1275E−02 
                 7.5929E−03 
               
               
                   
               
            
           
         
       
     
     In the 3rd embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 3rd embodiment, so an explanation in this regard will not be provided again. 
     Moreover, these parameters can be calculated from Table 5 and Table 6 as the following values and satisfy the following conditions: 
     
       
         
           
               
             
               
                   
               
               
                 3rd Embodiment 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 f [mm] 
                 1.22 
                 T12/(T34 + T45 + T56) 
                 2.64 
               
               
                   
                 Fno 
                 2.29 
                 TL/sin(HFOV × 1.6) [mm] 
                 4.01 
               
               
                   
                 HFOV [deg.] 
                 59.3 
                 CT5/|Sag52| 
                 2.48 
               
               
                   
                 tan(HFOV) 
                 1.68 
                 R11/f 
                 0.57 
               
               
                   
                 Nmax 
                 1.639 
                 |f1|/f2 
                 0.28 
               
               
                   
                 T12/T23 
                 3.44 
                 f6/f4 
                 2.20 
               
               
                   
                   
               
            
           
         
       
     
     Furthermore, according to the 3rd embodiment, when a central thickness of the first lens element  310  is CT1, a central thickness of the second lens element  320  is CT2, a central thickness of the third lens element  330  is CT3, a central thickness of the fourth lens element  340  is CT4, and a central thickness of the sixth lens element  360  is CT6, the following conditions are satisfied: CT1&lt;CT2; CT1&lt;CT3; CT1&lt;CT4; and CT1&lt;CT6. 
     According to the 3rd embodiment, when the focal length of the first lens element  310  is f1, the focal length of the second lens element  320  is f2, a focal length of the third lens element  330  is f3, the focal length of the fourth lens element  340  is f4, a focal length of the fifth lens element  350  is f5, and the focal length of the sixth lens element  360  is f6, the following conditions are satisfied: |f5|&lt;|f1|; |f5|&lt;|f2|; |f5|&lt;|f3|; |f5|&lt;|f4|; and |f5|&lt;|f6|. 
     4th Embodiment 
       FIG. 7  is a schematic view of an image capturing device according to the 4th embodiment of the present disclosure.  FIG. 8  shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing device according to the 4th embodiment. In  FIG. 7 , the image capturing device includes an optical lens (its reference numeral is omitted) and an image sensor  490 . The optical lens includes, in order from an object side to an image side, a first lens element  410 , a second lens element  420 , an aperture stop  400 , a third lens element  430 , a fourth lens element  440 , a fifth lens element  450 , a sixth lens element  460 , an IR-cut filter  470  and an image surface  480 , wherein the image sensor  490  is disposed on the image surface  480  of the optical lens. The optical lens has a total of sixth lens elements ( 410 - 460 ) with refractive power, and there is an air space between every two lens elements of the first lens element  410 , the second lens element  420 , the third lens element  430 , the fourth lens element  440 , the fifth lens element  450  and the sixth lens element  460  that are adjacent to each other. 
     The first lens element  410  with negative refractive power has an object-side surface  411  being convex in a paraxial region thereof and an image-side surface  412  being concave in a paraxial region thereof. The first lens element  410  is made of plastic material, and has the object-side surface  411  and the image-side surface  412  being both aspheric. 
     The second lens element  420  with positive refractive power has an object-side surface  421  being convex in a paraxial region thereof and an image-side surface  422  being concave in a paraxial region thereof. The second lens element  420  is made of plastic material, and has the object-side surface  421  and the image-side surface  422  being both aspheric. 
     The third lens element  430  with positive refractive power has an object-side surface  431  being convex in a paraxial region thereof and an image-side surface  432  being convex in a paraxial region thereof. The third lens element  430  is made of plastic material, and has the object-side surface  431  and the image-side surface  432  being both aspheric. 
     The fourth lens element  440  with positive refractive power has an object-side surface  441  being convex in a paraxial region thereof, and an image-side surface  442  being convex in a paraxial region thereof and including at least one concave shape in an off-axis region thereof. The fourth lens element  440  is made of plastic material, and has the object-side surface  441  and the image-side surface  442  being both aspheric. 
     The fifth lens element  450  with negative refractive power has an object-side surface  451  being concave in a paraxial region thereof, and an image-side surface  452  being concave in a paraxial region thereof and including at least one convex shape in an off-axis region thereof. The fifth lens element  450  is made of plastic material, and has the object-side surface  451  and the image-side surface  452  being both aspheric. 
     The sixth lens element  460  with positive refractive power has an object-side surface  461  being convex in a paraxial region thereof, and an image-side surface  462  being concave in a paraxial region thereof and including at least one convex shape in an off-axis region thereof. The sixth lens element  460  is made of plastic material, and has the object-side surface  461  and the image-side surface  462  being both aspheric. 
     The IR-cut filter  470  is made of glass material and located between the sixth lens element  460  and the image surface  480 , and will not affect a focal length of the optical lens. 
     The detailed optical data of the 4th embodiment are shown in Table 7 and the aspheric surface data are shown in Table 8 below. 
     
       
         
           
               
             
               
                 TABLE 7 
               
             
            
               
                   
               
               
                 4th Embodiment 
               
               
                 f = 1.21 mm, Fno = 2.29, HFOV = 62.5 deg. 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Curvature 
                   
                   
                   
                   
                 Focal 
               
               
                 Surface # 
                   
                 Radius 
                 Thickness 
                 Material 
                 Index 
                 Abbe # 
                 Length 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 0 
                 Object 
                 Plano 
                 Infinity 
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 1 
                 Lens 1 
                 2.320 
                 ASP 
                 0.255 
                 Plastic 
                 1.544 
                 55.9 
                 −1.64 
               
               
                 2 
                   
                 0.618 
                 ASP 
                 0.350 
               
               
                 3 
                 Lens 2 
                 0.971 
                 ASP 
                 0.330 
                 Plastic 
                 1.639 
                 23.5 
                 11.15 
               
               
                 4 
                   
                 0.975 
                 ASP 
                 0.233 
               
            
           
           
               
               
               
               
               
            
               
                 5 
                 Ape. Stop 
                 Plano 
                 −0.016 
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 6 
                 Lens 3 
                 3.083 
                 ASP 
                 0.402 
                 Plastic 
                 1.544 
                 55.9 
                 2.30 
               
               
                 7 
                   
                 −2.008 
                 ASP 
                 0.079 
               
               
                 8 
                 Lens 4 
                 1.693 
                 ASP 
                 0.544 
                 Plastic 
                 1.544 
                 55.9 
                 1.18 
               
               
                 9 
                   
                 −0.923 
                 ASP 
                 0.085 
               
               
                 10 
                 Lens 5 
                 −1.050 
                 ASP 
                 0.255 
                 Plastic 
                 1.639 
                 23.5 
                 −1.00 
               
               
                 11 
                   
                 1.784 
                 ASP 
                 0.114 
               
               
                 12 
                 Lens 6 
                 0.585 
                 ASP 
                 0.602 
                 Plastic 
                 1.544 
                 55.9 
                 1.47 
               
               
                 13 
                   
                 1.387 
                 ASP 
                 0.400 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 14 
                 IR-cut filter 
                 Plano 
                 0.110 
                 Glass 
                 1.517 
                 64.2 
                 — 
               
               
                 15 
                   
                 Plano 
                 0.278 
               
               
                 16 
                 Image 
                 Plano 
                 — 
               
               
                   
               
               
                 Note: 
               
               
                 Reference wavelength is 587.6 nm (d-line). 
               
               
                 An effective radius of surface 9 is 0.680 mm. 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 8 
               
               
                   
               
               
                 Aspheric Coefficients 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                   
                 Surface # 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 1 
                 2 
                 3 
                 4 
                 6 
                 7 
               
               
                   
               
               
                 k = 
                 7.8130E−01 
                 −5.9483E−01 
                 4.1545E−02 
                 −4.2152E+00 
                 −7.1386E+01 
                 6.7053E+00 
               
               
                 A4 = 
                 2.8900E−01 
                 2.8338E−01 
                 −1.2832E−01 
                 1.3309E+00 
                 2.0773E−01 
                 −1.5676E+00 
               
               
                 A6 = 
                 −7.8629E−01 
                 −3.3970E−01 
                 1.5512E+00 
                 4.4136E+00 
                 4.4017E−01 
                 4.0307E+00 
               
               
                 A8 = 
                 7.9195E−01 
                 −1.1156E+01 
                 −1.7799E+01 
                 −5.1361E+01 
                 −9.1240E+00 
                 −1.6428E+01 
               
               
                 A10 = 
                 −3.6265E−01 
                 2.7921E+01 
                 6.4628E+01 
                 4.9786E+02 
                 3.6220E+01 
                 2.6340E+01 
               
               
                 A12 = 
                 6.3971E−02 
                 −1.8875E+01 
                 −7.2674E+01 
                 −9.6417E+02 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 Surface # 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 8 
                 9 
                 10 
                 11 
                 12 
                 13 
               
               
                   
               
               
                 k = 
                 −5.9166E−01 
                 −2.6962E−01 
                 −4.8300E−01 
                 −9.0000E+01 
                 −6.0422E+00 
                 −4.9498E−01 
               
               
                 A4 = 
                 −1.1343E+00 
                 1.7989E+00 
                 2.4056E+00 
                 −3.2929E−01 
                 −1.9229E−01 
                 −2.1528E−01 
               
               
                 A6 = 
                 3.5339E+00 
                 −1.6929E+01 
                 −2.1501E+01 
                 3.3271E−01 
                 −2.6572E−01 
                 −2.3782E−01 
               
               
                 A8 = 
                 −1.1338E+01 
                 6.4067E+01 
                 7.8220E+01 
                 5.1354E−02 
                 9.8844E−01 
                 5.8855E−01 
               
               
                 A10 = 
                 1.3852E+01 
                 −1.2192E+02 
                 −1.6934E+02 
                 −9.8256E−01 
                 −1.4276E+00 
                 −6.2474E−01 
               
               
                 A12 = 
                   
                 9.6765E+01 
                 2.1172E+02 
                 1.5261E+00 
                 9.1548E−01 
                 3.5322E−01 
               
               
                 A14 = 
                   
                   
                 −1.0877E+02 
                 −6.8369E−01 
                 −2.1057E−01 
                 −1.0456E−01 
               
               
                 A16 = 
                   
                   
                   
                   
                   
                 1.2796E−02 
               
               
                   
               
            
           
         
       
     
     In the 4th embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 4th embodiment, so an explanation in this regard will not be provided again. 
     Moreover, these parameters can be calculated from Table 7 and Table 8 as the following values and satisfy the following conditions: 
     
       
         
           
               
             
               
                   
               
               
                 4th Embodiment 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 f [mm] 
                 1.21 
                 T12/(T34 + T45 + T56) 
                 1.26 
               
               
                   
                 Fno 
                 2.29 
                 TL/sin(HFOV × 1.6) [mm] 
                 4.08 
               
               
                   
                 HFOV [deg.] 
                 62.5 
                 CT5/|Sag52| 
                 42.10 
               
               
                   
                 tan(HFOV) 
                 1.92 
                 R11/f 
                 0.48 
               
               
                   
                 Nmax 
                 1.639 
                 |f1|/f2 
                 0.15 
               
               
                   
                 T12/T23 
                 1.61 
                 f6/f4 
                 1.25 
               
               
                   
                   
               
            
           
         
       
     
     Furthermore, according to the 4th embodiment, when a central thickness of the first lens element  410  is CT1, a central thickness of the second lens element  420  is CT2, a central thickness of the third lens element  430  is CT3, a central thickness of the fourth lens element  440  is CT4, and a central thickness of the sixth lens element  460  is CT6, the following conditions are satisfied: CT1&lt;CT2; CT1&lt;CT3; CT1&lt;CT4; and CT1&lt;CT6. 
     According to the 4th embodiment, when the focal length of the first lens element  410  is f1, the focal length of the second lens element  420  is f2, a focal length of the third lens element  430  is f3, the focal length of the fourth lens element  440  is f4, a focal length of the fifth lens element  450  is f5, and the focal length of the sixth lens element  460  is f6, the following conditions are satisfied: |f5|&lt;|f1|; |f5|&lt;|f2|; |f5|&lt;|f3|; |f5|&lt;|f4|; and |f5|&lt;|f6|. 
     5th Embodiment 
       FIG. 9  is a schematic view of an image capturing device according to the 5th embodiment of the present disclosure.  FIG. 10  shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing device according to the 5th embodiment. In  FIG. 9 , the image capturing device includes an optical lens (its reference numeral is omitted) and an image sensor  590 . The optical lens includes, in order from an object side to an image side, a first lens element  510 , a second lens element  520 , an aperture stop  500 , a third lens element  530 , a fourth lens element  540 , a fifth lens element  550 , a sixth lens element  560 , an IR-cut filter  570  and an image surface  580 , wherein the image sensor  590  is disposed on the image surface  580  of the optical lens. The optical lens has a total of sixth lens elements ( 510 - 560 ) with refractive power, and there is an air space between every two lens elements of the first lens element  510 , the second lens element  520 , the third lens element  530 , the fourth lens element  540 , the fifth lens element  550  and the sixth lens element  560  that are adjacent to each other. 
     The first lens element  510  with negative refractive power has an object-side surface  511  being convex in a paraxial region thereof and an image-side surface  512  being concave in a paraxial region thereof. The first lens element  510  is made of plastic material, and has the object-side surface  511  and the image-side surface  512  being both aspheric. 
     The second lens element  520  with positive refractive power has an object-side surface  521  being convex in a paraxial region thereof and an image-side surface  522  being concave in a paraxial region thereof. The second lens element  520  is made of plastic material, and has the object-side surface  521  and the image-side surface  522  being both aspheric. 
     The third lens element  530  with positive refractive power has an object-side surface  531  being convex in a paraxial region thereof and an image-side surface  532  being convex in a paraxial region thereof. The third lens element  530  is made of plastic material, and has the object-side surface  531  and the image-side surface  532  being both aspheric. 
     The fourth lens element  540  with positive refractive power has an object-side surface  541  being convex in a paraxial region thereof, and an image-side surface  542  being convex in a paraxial region thereof and including at least one concave shape in an off-axis region thereof. The fourth lens element  540  is made of plastic material, and has the object-side surface  541  and the image-side surface  542  being both aspheric. 
     The fifth lens element  550  with negative refractive power has an object-side surface  551  being concave in a paraxial region thereof, and an image-side surface  552  being concave in a paraxial region thereof and including at least one convex shape in an off-axis region thereof. The fifth lens element  550  is made of plastic material, and has the object-side surface  551  and the image-side surface  552  being both aspheric. 
     The sixth lens element  560  with positive refractive power has an object-side surface  561  being convex in a paraxial region thereof, and an image-side surface  562  being concave in a paraxial region thereof and including at least one convex shape in an off-axis region thereof. The sixth lens element  560  is made of plastic material, and has the object-side surface  561  and the image-side surface  562  being both aspheric. 
     The IR-cut filter  570  is made of glass material and located between the sixth lens element  560  and the image surface  580 , and will not affect a focal length of the optical lens. 
     The detailed optical data of the 5th embodiment are shown in Table 9 and the aspheric surface data are shown in Table 10 below. 
     
       
         
           
               
             
               
                 TABLE 9 
               
             
            
               
                   
               
               
                 5th Embodiment 
               
               
                 f = 1.30 mm, Fno = 2.67, HFOV = 58.6 deg. 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Curvature 
                   
                   
                   
                   
                 Focal 
               
               
                 Surface # 
                   
                 Radius 
                 Thickness 
                 Material 
                 Index 
                 Abbe # 
                 Length 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 0 
                 Object 
                 Plano 
                 Infinity 
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 1 
                 Lens 1 
                 2.023 
                 ASP 
                 0.322 
                 Plastic 
                 1.544 
                 55.9 
                 −1.79 
               
               
                 2 
                   
                 0.620 
                 ASP 
                 0.487 
               
               
                 3 
                 Lens 2 
                 1.073 
                 ASP 
                 0.401 
                 Plastic 
                 1.544 
                 55.9 
                 23.56 
               
               
                 4 
                   
                 1.017 
                 ASP 
                 0.275 
               
            
           
           
               
               
               
               
               
            
               
                 5 
                 Ape. Stop 
                 Plano 
                 −0.007 
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 6 
                 Lens 3 
                 3.574 
                 ASP 
                 0.480 
                 Plastic 
                 1.544 
                 55.9 
                 1.48 
               
               
                 7 
                   
                 −0.992 
                 ASP 
                 0.090 
               
               
                 8 
                 Lens 4 
                 9.424 
                 ASP 
                 0.689 
                 Plastic 
                 1.514 
                 56.8 
                 2.30 
               
               
                 9 
                   
                 −1.317 
                 ASP 
                 0.070 
               
               
                 10 
                 Lens 5 
                 −1.747 
                 ASP 
                 0.256 
                 Plastic 
                 1.633 
                 23.4 
                 −1.03 
               
               
                 11 
                   
                 1.097 
                 ASP 
                 0.047 
               
               
                 12 
                 Lens 6 
                 0.638 
                 ASP 
                 0.650 
                 Plastic 
                 1.514 
                 56.8 
                 1.30 
               
               
                 13 
                   
                 8.806 
                 ASP 
                 0.419 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 14 
                 IR-cut filter 
                 Plano 
                 0.210 
                 Glass 
                 1.517 
                 64.2 
                 — 
               
               
                 15 
                   
                 Plano 
                 0.339 
               
               
                 16 
                 Image 
                 Plano 
                 — 
               
               
                   
               
               
                 Note: 
               
               
                 Reference wavelength is 587.6 nm (d-line). 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 10 
               
               
                   
               
               
                 Aspheric Coefficients 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                   
                 Surface # 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 1 
                 2 
                 3 
                 4 
                 6 
                 7 
               
               
                   
               
               
                 k = 
                 −2.0725E−01 
                 −7.7056E−01 
                 −8.9818E−01 
                 −1.4271E+00 
                 1.3871E+01 
                 −7.4081E+00 
               
               
                 A4 = 
                 5.4356E−01 
                 1.0635E+00 
                 5.9066E−01 
                 1.3894E+00 
                 1.5132E−01 
                 −7.5658E−01 
               
               
                 A6 = 
                 −3.7707E−01 
                 5.0337E+00 
                 −1.9431E−01 
                 −5.0234E−01 
                 1.2553E+00 
                 9.1358E−01 
               
               
                 A8 = 
                 −8.1544E−01 
                 −3.0709E+01 
                 −3.2505E+00 
                 2.2564E+01 
                   
                 −4.5976E+00 
               
               
                 A10 = 
                 1.3551E+00 
                 4.8092E+01 
                 1.2352E+01 
                   
                   
                 1.6644E+01 
               
               
                 A12 = 
                 −8.4009E−01 
                 −2.4586E+01 
                 −1.6255E+01 
               
               
                 A14 = 
                 2.4775E−01 
               
               
                 A16 = 
                 −2.9100E−02 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 Surface # 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 8 
                 9 
                 10 
                 11 
                 12 
                 13 
               
               
                   
               
               
                 k = 
                 −1.0000E+00 
                 6.9670E−01 
                 3.1445E+00 
                 −2.6303E+01 
                 −8.0662E+00 
                 −9.0000E+01 
               
               
                 A4 = 
                 2.7536E−01 
                 −1.0297E+00 
                 −9.8651E−01 
                 −7.5148E−01 
                 −1.7347E−01 
                 4.3570E−01 
               
               
                 A6 = 
                 −1.4776E+00 
                 2.1355E+00 
                 8.0863E−01 
                 1.7909E+00 
                 −6.3705E−01 
                 −9.8302E−01 
               
               
                 A8 = 
                 1.7478E+00 
                 −4.7271E+00 
                 1.1921E−01 
                 −2.5593E+00 
                 2.2611E+00 
                 9.3570E−01 
               
               
                 A10 = 
                 −2.0969E+00 
                 1.1722E+01 
                 7.5234E−01 
                 2.0751E+00 
                 −3.8900E+00 
                 −4.9009E−01 
               
               
                 A12 = 
                   
                 −2.0367E+01 
                   
                 −6.9997E−01 
                 3.2250E+00 
                 1.0944E−01 
               
               
                 A14 = 
                   
                 1.5358E+01 
                   
                   
                 −9.9070E−01 
               
               
                   
               
            
           
         
       
     
     In the 5th embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 5th embodiment, so an explanation in this regard will not be provided again. 
     Moreover, these parameters can be calculated from Table 9 and Table 10 as the following values and satisfy the following conditions: 
     
       
         
           
               
             
               
                   
               
               
                 5th Embodiment 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 f [mm] 
                 1.30 
                 T12/(T34 + T45 + T56) 
                 2.35 
               
               
                   
                 Fno 
                 2.67 
                 TL/sin(HFOV × 1.6) [mm] 
                 4.74 
               
               
                   
                 HFOV [deg.] 
                 58.6 
                 CT5/|Sag52| 
                 21.11 
               
               
                   
                 tan(HFOV) 
                 1.64 
                 R11/f 
                 0.49 
               
               
                   
                 Nmax 
                 1.633 
                 |f1|/f2 
                 0.08 
               
               
                   
                 T12/T23 
                 1.82 
                 f6/f4 
                 0.57 
               
               
                   
                   
               
            
           
         
       
     
     Furthermore, according to the 5th embodiment, when a central thickness of the first lens element  510  is CT1, a central thickness of the second lens element  520  is CT2, a central thickness of the third lens element  530  is CT3, a central thickness of the fourth lens element  540  is CT4, and a central thickness of the sixth lens element  560  is CT6, the following conditions are satisfied: CT1&lt;CT2; CT1&lt;CT3; CT1&lt;CT4; and CT1&lt;CT6. 
     According to the 5th embodiment, when the focal length of the first lens element  510  is f1, the focal length of the second lens element  520  is f2, a focal length of the third lens element  530  is f3, the focal length of the fourth lens element  540  is f4, a focal length of the fifth lens element  550  is f5, and the focal length of the sixth lens element  560  is f6, the following conditions are satisfied: |f5|&lt;|f1|; |f5|&lt;|f2|; |f5|&lt;|f3|; |f5|&lt;|f4|; and |f5|&lt;|f6|. 
     6th Embodiment 
       FIG. 11  is a schematic view of an image capturing device according to the 6th embodiment of the present disclosure.  FIG. 12  shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing to device according to the 6th embodiment. In  FIG. 11 , the image capturing device includes an optical lens (its reference numeral is omitted) and an image sensor  690 . The optical lens includes, in order from an object side to an image side, a first lens element  610 , a second lens element  620 , an aperture stop  600 , a third lens element  630 , a fourth lens element  640 , a fifth lens element  650 , a sixth lens element  660 , an IR-cut filter  670  and an image surface  680 , wherein the image sensor  690  is disposed on the image surface  680  of the optical lens. The optical lens has a total of sixth lens elements ( 610 - 660 ) with refractive power, and there is an air space between every two lens elements of the first lens element  610 , the second lens element  620 , the third lens element  630 , the fourth lens element  640 , the fifth lens element  650  and the sixth lens element  660  that are adjacent to each other. 
     The first lens element  610  with negative refractive power has an object-side surface  611  being convex in a paraxial region thereof and an image-side surface  612  being concave in a paraxial region thereof. The first lens element  610  is made of plastic material, and has the object-side surface  611  and the image-side surface  612  being both aspheric. 
     The second lens element  620  with positive refractive power has an object-side surface  621  being convex in a paraxial region thereof and an image-side surface  622  being concave in a paraxial region thereof. The second lens element  620  is made of plastic material, and has the object-side surface  621  and the image-side surface  622  being both aspheric. 
     The third lens element  630  with positive refractive power has an object-side surface  631  being concave in a paraxial region thereof and an image-side surface  632  being convex in a paraxial region thereof. The third lens element  630  is made of plastic material, and has the object-side surface  631  and the image-side surface  632  being both aspheric. 
     The fourth lens element  640  with positive refractive power has an object-side surface  641  being convex in a paraxial region thereof, and an image-side surface  642  being convex in a paraxial region thereof and including at least one concave shape in an off-axis region thereof. The fourth lens element  640  is made of plastic material, and has the object-side surface  641  and the image-side surface  642  being both aspheric. 
     The fifth lens element  650  with negative refractive power has an object-side surface  651  being concave in a paraxial region thereof, and an image-side surface  652  being concave in a paraxial region thereof and including at least one convex shape in an off-axis region thereof. The fifth lens element  650  is made of plastic material, and has the object-side surface  651  and the image-side surface  652  being both aspheric. 
     The sixth lens element  660  with positive refractive power has an object-side surface  661  being convex in a paraxial region thereof, and an image-side surface  662  being concave in a paraxial region thereof and including at least one convex shape in an off-axis region thereof. The sixth lens element  660  is made of plastic material, and has the object-side surface  661  and the image-side surface  662  being both aspheric. 
     The IR-cut filter  670  is made of glass material and located between the sixth lens element  660  and the image surface  680 , and will not affect a focal length of the optical lens. 
     The detailed optical data of the 6th embodiment are shown in Table 11 and the aspheric surface data are shown in Table 12 below. 
     
       
         
           
               
             
               
                 TABLE 11 
               
             
            
               
                   
               
               
                 6th Embodiment 
               
               
                 f = 1.02 mm, Fno = 2.45, HFOV = 60.8 deg. 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Curvature 
                   
                   
                   
                   
                 Focal 
               
               
                 Surface # 
                   
                 Radius 
                 Thickness 
                 Material 
                 Index 
                 Abbe # 
                 Length 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 0 
                 Object 
                 Plano 
                 Infinity 
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 1 
                 Lens 1 
                 1.401 
                 ASP 
                 0.299 
                 Plastic 
                 1.544 
                 55.9 
                 −1.68 
               
               
                 2 
                   
                 0.511 
                 ASP 
                 0.646 
               
               
                 3 
                 Lens 2 
                 1.392 
                 ASP 
                 0.313 
                 Plastic 
                 1.639 
                 23.5 
                 8.35 
               
               
                 4 
                   
                 1.718 
                 ASP 
                 0.215 
               
            
           
           
               
               
               
               
               
            
               
                 5 
                 Ape. Stop 
                 Plano 
                 0.009 
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 6 
                 Lens 3 
                 −27.171 
                 ASP 
                 0.391 
                 Plastic 
                 1.544 
                 55.9 
                 1.72 
               
               
                 7 
                   
                 −0.910 
                 ASP 
                 0.030 
               
               
                 8 
                 Lens 4 
                 6.707 
                 ASP 
                 0.694 
                 Plastic 
                 1.544 
                 55.9 
                 1.35 
               
               
                 9 
                   
                 −0.793 
                 ASP 
                 0.050 
               
               
                 10 
                 Lens 5 
                 −0.732 
                 ASP 
                 0.255 
                 Plastic 
                 1.639 
                 23.5 
                 −1.12 
               
               
                 11 
                   
                 31.702 
                 ASP 
                 0.169 
               
               
                 12 
                 Lens 6 
                 0.892 
                 ASP 
                 0.716 
                 Plastic 
                 1.544 
                 55.9 
                 1.75 
               
               
                 13 
                   
                 9.800 
                 ASP 
                 0.400 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 14 
                 IR-cut filter 
                 Plano 
                 0.175 
                 Glass 
                 1.517 
                 64.2 
                 — 
               
               
                 15 
                   
                 Plano 
                 0.144 
               
               
                 16 
                 Image 
                 Plano 
                 — 
               
               
                   
               
               
                 Note: 
               
               
                 Reference wavelength is 587.6 nm (d-line). 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 12 
               
               
                   
               
               
                 Aspheric Coefficients 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                   
                 Surface # 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 1 
                 2 
                 3 
                 4 
                 6 
                 7 
               
               
                   
               
               
                 k = 
                 −7.2280E−01 
                 −8.2265E−01 
                 1.0556E+00 
                 −1.6190E−01 
                 −1.6902E+00 
                 −3.7511E+00 
               
               
                 A4 = 
                 4.5660E−01 
                 1.2387E+00 
                 2.6898E−01 
                 7.2144E−01 
                 −8.1192E−02 
                 −8.0299E−01 
               
               
                 A6 = 
                 −8.9294E−01 
                 −1.8232E+00 
                 −7.0173E−01 
                 1.1657E+00 
                 −1.0288E+00 
                 8.1596E−01 
               
               
                 A8 = 
                 6.6692E−01 
                 −1.8477E+00 
                 4.1425E+00 
                   
                   
                 −9.7803E+00 
               
               
                 A10 = 
                 −2.3791E−01 
                 5.1098E+00 
                 −1.4525E+01 
                   
                   
                 1.6998E+01 
               
               
                 A12 = 
                 3.4841E−02 
                 −3.6346E+00 
                 1.0261E+01 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 Surface # 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 8 
                 9 
                 10 
                 11 
                 12 
                 13 
               
               
                   
               
               
                 k = 
                 2.8629E+01 
                 −2.0402E−01 
                 −3.7018E−01 
                 −4.6244E+01 
                 −9.0434E+00 
                 2.5798E+01 
               
               
                 A4 = 
                 9.2036E−03 
                 3.4702E−01 
                 4.9769E−01 
                 −8.4049E−01 
                 1.3285E−01 
                 6.5205E−01 
               
               
                 A6 = 
                 1.9368E−01 
                 −4.1459E+00 
                 −2.4155E+00 
                 3.7007E+00 
                 −1.2879E+00 
                 −1.7680E+00 
               
               
                 A8 = 
                 −3.1301E+00 
                 1.5437E+01 
                 3.4205E+00 
                 −9.3997E+00 
                 2.8636E+00 
                 2.3002E+00 
               
               
                 A10 = 
                 4.8334E+00 
                 −2.7104E+01 
                   
                 1.3466E+01 
                 −3.4864E+00 
                 −1.7911E+00 
               
               
                 A12 = 
                   
                 1.9704E+01 
                   
                 −1.0021E+01 
                 2.0658E+00 
                 8.0827E−01 
               
               
                 A14 = 
                   
                   
                   
                 3.0873E+00 
                 −4.5765E−01 
                 −1.9367E−01 
               
               
                 A16 = 
                   
                   
                   
                   
                   
                 1.9083E−02 
               
               
                   
               
            
           
         
       
     
     In the 6th embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 6th embodiment, so an explanation in this regard will not be provided again. 
     Moreover, these parameters can be calculated from Table 11 and Table 12 as the following values and satisfy the following conditions: 
     
       
         
           
               
             
               
                   
               
               
                 6th Embodiment 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 f [mm] 
                 1.02 
                 T12/(T34 + T45 + T56) 
                 2.59 
               
               
                   
                 Fno 
                 2.45 
                 TL/sin(HFOV × 1.6) [mm] 
                 4.54 
               
               
                   
                 HFOV [deg.] 
                 60.8 
                 CT5/|Sag52| 
                 5.26 
               
               
                   
                 tan(HFOV) 
                 1.79 
                 R11/f 
                 0.87 
               
               
                   
                 Nmax 
                 1.639 
                 |f1|/f2 
                 0.20 
               
               
                   
                 T12/T23 
                 2.88 
                 f6/f4 
                 1.30 
               
               
                   
                   
               
            
           
         
       
     
     Furthermore, according to the 6th embodiment, when a central thickness of the first lens element  610  is CT1, a central thickness of the second lens element  620  is CT2, a central thickness of the third lens element  630  is CT3, a central thickness of the fourth lens element  640  is CT4, and a central thickness of the sixth lens element  660  is CT6, the following conditions are satisfied: CT1&lt;CT2; CT1&lt;CT3; CT1&lt;CT4; and CT1&lt;CT6. 
     According to the 6th embodiment, when the focal length of the first lens element  610  is f1, the focal length of the second lens element  620  is f2, a focal length of the third lens element  630  is f3, the focal length of the fourth lens element  640  is f4, a focal length of the fifth lens element  650  is f5, and the focal length of the sixth lens element  660  is f6, the following conditions are satisfied: |f5|&lt;|f1|; |f5|&lt;|f2|; |f5|&lt;|f3|; |f5|&lt;|f4|; and |f5|&lt;|f6|. 
     7th Embodiment 
       FIG. 13  is a schematic view of an image capturing device according to the 7th embodiment of the present disclosure.  FIG. 14  shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing device according to the 7th embodiment. In  FIG. 13 , the image capturing device includes an optical lens (its reference numeral is omitted) and an image sensor  790 . The optical lens includes, in order from an object side to an image side, a first lens element  710 , a second lens element  720 , an aperture stop  700 , a third lens element  730 , a fourth lens element  740 , a fifth lens element  750 , a sixth lens element  760 , an IR-cut filter  770  and an image surface  780 , wherein the image sensor  790  is disposed on the image surface  780  of the optical lens. The optical lens has a total of sixth lens elements ( 710 - 760 ) with refractive power, and there is an air space between every two lens elements of the first lens element  710 , the second lens element  720 , the third lens element  730 , the fourth lens element  740 , the fifth lens element  750  and the sixth lens element  760  that are adjacent to each other. 
     The first lens element  710  with negative refractive power has an object-side surface  711  being convex in a paraxial region thereof and an image-side surface  712  being concave in a paraxial region thereof. The first lens element  710  is made of plastic material, and has the object-side surface  711  and the image-side surface  712  being both aspheric. 
     The second lens element  720  with positive refractive power has an object-side surface  721  being convex in a paraxial region thereof and an image-side surface  722  being concave in a paraxial region thereof. The second lens element  720  is made of plastic material, and has the object-side surface  721  and the image-side surface  722  being both aspheric. 
     The third lens element  730  with positive refractive power has an object-side surface  731  being concave in a paraxial region thereof and an image-side surface  732  being convex in a paraxial region thereof. The third lens element  730  is made of plastic material, and has the object-side surface  731  and the image-side surface  732  being both aspheric. 
     The fourth lens element  740  with positive refractive power has an object-side surface  741  being convex in a paraxial region thereof, and an image-side surface  742  being convex in a paraxial region thereof and including at least one concave shape in an off-axis region thereof. The fourth lens element  740  is made of plastic material, and has the object-side surface  741  and the image-side surface  742  being both aspheric. 
     The fifth lens element  750  with negative refractive power has an object-side surface  751  being concave in a paraxial region thereof, and an image-side surface  752  being concave in a paraxial region thereof and including at least one convex shape in an off-axis region thereof. The fifth lens element  750  is made of plastic material, and has the object-side surface  751  and the image-side surface  752  being both aspheric. 
     The sixth lens element  760  with positive refractive power has an object-side surface  761  being convex in a paraxial region thereof, and an image-side surface  762  being concave in a paraxial region thereof and including at least one convex shape in an off-axis region thereof. The sixth lens element  760  is made of plastic material, and has the object-side surface  761  and the image-side surface  762  being both aspheric. 
     The IR-cut filter  770  is made of glass material and located between the sixth lens element  760  and the image surface  780 , and will not affect a focal length of the optical lens. 
     The detailed optical data of the 7th embodiment are shown in Table 13 and the aspheric surface data are shown in Table 14 below. 
     
       
         
           
               
             
               
                 TABLE 13 
               
             
            
               
                   
               
               
                 7th Embodiment 
               
               
                 f = 1.29 mm, Fno = 2.45, HFOV = 53.6 deg. 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Curvature 
                   
                   
                   
                   
                 Focal 
               
               
                 Surface # 
                   
                 Radius 
                 Thickness 
                 Material 
                 Index 
                 Abbe # 
                 Length 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 0 
                 Object 
                 Plano 
                 Infinity 
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 1 
                 Lens 1 
                 1.053 
                 ASP 
                 0.419 
                 Plastic 
                 1.639 
                 23.5 
                 −2.35 
               
               
                 2 
                   
                 0.523 
                 ASP 
                 0.645 
               
               
                 3 
                 Lens 2 
                 0.954 
                 ASP 
                 0.372 
                 Plastic 
                 1.639 
                 23.5 
                 5.76 
               
               
                 4 
                   
                 1.092 
                 ASP 
                 0.179 
               
            
           
           
               
               
               
               
               
            
               
                 5 
                 Ape. Stop 
                 Plano 
                 0.015 
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 6 
                 Lens 3 
                 −24.558 
                 ASP 
                 0.388 
                 Plastic 
                 1.544 
                 55.9 
                 1.72 
               
               
                 7 
                   
                 −0.906 
                 ASP 
                 0.030 
               
               
                 8 
                 Lens 4 
                 64.598 
                 ASP 
                 0.627 
                 Plastic 
                 1.544 
                 55.9 
                 1.52 
               
               
                 9 
                   
                 −0.836 
                 ASP 
                 0.088 
               
               
                 10 
                 Lens 5 
                 −0.800 
                 ASP 
                 0.255 
                 Plastic 
                 1.639 
                 23.5 
                 −1.23 
               
               
                 11 
                   
                 64.792 
                 ASP 
                 0.234 
               
               
                 12 
                 Lens 6 
                 0.866 
                 ASP 
                 0.508 
                 Plastic 
                 1.544 
                 55.9 
                 1.76 
               
               
                 13 
                   
                 6.981 
                 ASP 
                 0.400 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 14 
                 IR-cut filter 
                 Plano 
                 0.175 
                 Glass 
                 1.517 
                 64.2 
                 — 
               
               
                 15 
                   
                 Plano 
                 0.165 
               
               
                 16 
                 Image 
                 Plano 
                 — 
               
               
                   
               
               
                 Note: 
               
               
                 Reference wavelength is 587.6 nm (d-line). 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 14 
               
               
                   
               
               
                 Aspheric Coefficients 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                   
                 Surface # 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 1 
                 2 
                 3 
                 4 
                 6 
                 7 
               
               
                   
               
               
                 k = 
                 −7.9961E−01 
                 −9.2372E−01 
                 −4.6981E−01 
                 −2.0572E+00 
                 9.0000E+01 
                 −3.0190E+00 
               
               
                 A4 = 
                 2.6704E−01 
                 1.0873E+00 
                 1.8226E−01 
                 7.4636E−01 
                 −1.9195E−01 
                 −8.2824E−01 
               
               
                 A6 = 
                 −3.2493E−01 
                 −2.7674E+00 
                 −3.2860E−01 
                 2.9591E+00 
                 4.1991E−01 
                 1.7562E+00 
               
               
                 A8 = 
                 1.0129E−01 
                 4.0804E+00 
                 1.8865E+00 
                 −9.2903E+00 
                 −8.4388E+00 
                 −1.5303E+01 
               
               
                 A10 = 
                 −3.8568E−03 
                 −4.7303E+00 
                 −2.4587E+00 
                 6.0727E+01 
                 6.1832E+01 
                 2.9506E+01 
               
               
                 A12 = 
                 2.4739E−04 
                 2.1348E+00 
                 −8.2400E+00 
                 4.6348E−11 
                 5.9171E−10 
                 1.0882E−09 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 Surface # 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 8 
                 9 
                 10 
                 11 
                 12 
                 13 
               
               
                   
               
               
                 k = 
                 −9.0000E+01 
                 −2.0058E−01 
                 −1.6410E−01 
                 −1.0507E+01 
                 −8.7735E+00 
                 4.1138E+00 
               
               
                 A4 = 
                 −8.8337E−02 
                 5.8338E−01 
                 6.6686E−01 
                 −9.5887E−01 
                 3.3671E−01 
                 1.0091E+00 
               
               
                 A6 = 
                 7.7324E−01 
                 −4.6822E+00 
                 −2.4441E+00 
                 3.8936E+00 
                 −2.0298E+00 
                 −2.9874E+00 
               
               
                 A8 = 
                 −5.8411E+00 
                 1.5718E+01 
                 3.9527E+00 
                 −9.1121E+00 
                 3.6087E+00 
                 4.2223E+00 
               
               
                 A10 = 
                 8.1400E+00 
                 −2.7369E+01 
                 −7.9834E−01 
                 1.2486E+01 
                 −3.4418E+00 
                 −3.5670E+00 
               
               
                 A12 = 
                 −4.1564E−09 
                 1.9704E+01 
                 −1.2242E−08 
                 −8.9961E+00 
                 1.6617E+00 
                 1.7981E+00 
               
               
                 A14 = 
                   
                   
                   
                 2.6433E+00 
                 −3.1052E−01 
                 −5.0383E−01 
               
               
                 A16 = 
                   
                   
                   
                   
                   
                 6.0912E−02 
               
               
                   
               
            
           
         
       
     
     In the 7th embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 7th embodiment, so an explanation in this regard will not be provided again. 
     Moreover, these parameters can be calculated from Table 13 and Table 14 as the following values and satisfy the following conditions: 
     
       
         
           
               
             
               
                   
               
               
                 7th Embodiment 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 f [mm] 
                 1.29 
                 T12/(T34 + T45 + T56) 
                 1.83 
               
               
                   
                 Fno 
                 2.45 
                 TL/sin(HFOV × 1.6) [mm] 
                 4.51 
               
               
                   
                 HFOV [deg.] 
                 53.6 
                 CT5/|Sag52| 
                 4.57 
               
               
                   
                 tan(HFOV) 
                 1.36 
                 R11/f 
                 0.67 
               
               
                   
                 Nmax 
                 1.639 
                 |f1|/f2 
                 0.41 
               
               
                   
                 T12/T23 
                 3.32 
                 f6/f4 
                 1.16 
               
               
                   
                   
               
            
           
         
       
     
     Furthermore, according to the 7th embodiment, when the focal length of the first lens element  710  is f1, the focal length of the second lens element  720  is f2, a focal length of the third lens element  730  is f3, the focal length of the fourth lens element  740  is f4, a focal length of the fifth lens element  750  is f5, and the focal length of the sixth lens element  760  is f6, the following conditions are satisfied: |f5|&lt;|f1|; |f5|&lt;|f2|; |f5|&lt;|f3|; |f5|&lt;|f4|; and |f5|&lt;|f6|. 
     8th Embodiment 
       FIG. 16  is a schematic view of an electronic device  10  according to the 8th embodiment of the present disclosure. The electronic device  10  of the 8th embodiment is a smart phone, wherein the electronic device  10  includes an image capturing device  11 . The image capturing device  11  includes an optical lens (its reference numeral is omitted) according to the present disclosure and an image sensor (its reference numeral is omitted), wherein the image sensor is disposed on an image surface of the optical lens. 
     9th Embodiment 
       FIG. 17  is a schematic view of an electronic device  20  according to the 9th embodiment of the present disclosure. The electronic device  20  of the 9th embodiment is a tablet personal computer, wherein the electronic device  20  includes an image capturing device  21 . The image capturing device  21  includes an optical lens (its reference numeral is omitted) according to the present disclosure and an image sensor (Its reference numeral is omitted), wherein the image sensor is disposed on an image surface of the optical lens. 
     10th Embodiment 
       FIG. 18  is a schematic view of an electronic device  30  according to the 10th embodiment of the present disclosure. The electronic device  30  of the 10th embodiment is a wearable device, such as a head-mounted display (HMD), wherein the electronic device  30  includes an image capturing device  31 . The image capturing device  31  includes an optical lens (its reference numeral is omitted) according to the present disclosure and an image sensor (its reference numeral is omitted), wherein the image sensor is disposed on an image surface of the optical lens. 
     The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. It is to be noted that TABLES 1-14 show different data of the different embodiments; however, the data of the different embodiments are obtained from experiments. The embodiments were chosen and described in order to best explain the principles of the disclosure and its practical applications, to thereby enable others skilled in the art to best utilize the disclosure and various embodiments with various modifications as are suited to the particular use contemplated. The embodiments depicted above and the appended drawings are exemplary and are not intended to be exhaustive or to limit the scope of the present disclosure to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings.