Patent Publication Number: US-2021191088-A1

Title: Wide-angle lens

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present invention claims priority under 35 U.S.C. § 119 to Chinese Application No. 201911281254.4 filed on Dec. 13, 2019, the entire content of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The disclosure relates to a wide-angle lens. 
     BACKGROUND 
     As a wide-angle lens for an in-vehicle camera, there has conventionally been a wide-angle lens including, sequentially arranged from an object side, a first lens, a second lens, a third lens, a fourth lens, a diaphragm, a fifth lens, a sixth lens and a seventh lens. 
     In practice, sometimes the space for mounting the wide-angle lens in a vehicle may have a limited length in the optical axis direction of the wide-angle lens. Therefore, it has been desired to ensure the optical performance of the wide-angle lens while preventing the overall length of the wide-angle lens from becoming excessively large. 
     SUMMARY 
     An exemplary embodiment of the disclosure provides a wide-angle lens, including a first lens, a second lens, a third lens, a fourth lens, a diaphragm, a fifth lens, a sixth lens, and a seventh lens, sequentially arranged from an object side. An object-to-image distance of the wide-angle lens is set to d, an entrance pupil diameter of the wide-angle lens is set to HEP, and d/HEP&lt;29.000 is satisfied. 
     The above and other elements, features, steps, characteristics and advantages of the present disclosure will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a wide-angle lens according to Embodiment 1 of the disclosure. 
         FIG. 2A  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 1 of the disclosure. 
         FIG. 2B  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 1 of the disclosure. 
         FIG. 3A  illustrates lateral chromatic aberration (transverse chromatic aberration) of the wide-angle lens according to Embodiment 1 of the disclosure. 
         FIG. 3B  illustrates spherical aberration (longitudinal aberration) of the wide-angle lens according to Embodiment 1 of the disclosure. 
         FIG. 4A  to  FIG. 4L  illustrate transverse aberration of the wide-angle lens according to Embodiment 1 of the disclosure. 
         FIG. 5  illustrates a wide-angle lens according to Embodiment 2 of the disclosure. 
         FIG. 6A  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 2 of the disclosure. 
         FIG. 6B  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 2 of the disclosure. 
         FIG. 7A  illustrates lateral chromatic aberration (transverse chromatic aberration) of the wide-angle lens according to Embodiment 2 of the disclosure. 
         FIG. 7B  illustrates spherical aberration (longitudinal aberration) of the wide-angle lens according to Embodiment 2 of the disclosure. 
         FIG. 8A  to  FIG. 8L  illustrate transverse aberration of the wide-angle lens according to Embodiment 2 of the disclosure. 
         FIG. 9  illustrates a wide-angle lens according to Embodiment 3 of the disclosure. 
         FIG. 10A  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 3 of the disclosure. 
         FIG. 10B  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 3 of the disclosure. 
         FIG. 11A  illustrates lateral chromatic aberration (transverse chromatic aberration) of the wide-angle lens according to Embodiment 3 of the disclosure. 
         FIG. 11B  illustrates spherical aberration (longitudinal aberration) of the wide-angle lens according to Embodiment 3 of the disclosure. 
         FIG. 12A  to  FIG. 12L  illustrate transverse aberration of the wide-angle lens according to Embodiment 3 of the disclosure. 
         FIG. 13  illustrates a wide-angle lens according to Embodiment 4 of the disclosure. 
         FIG. 14A  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 4 of the disclosure. 
         FIG. 14B  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 4 of the disclosure. 
         FIG. 15A  illustrates lateral chromatic aberration (transverse chromatic aberration) of the wide-angle lens according to Embodiment 4 of the disclosure. 
         FIG. 15B  illustrates spherical aberration (longitudinal aberration) of the wide-angle lens according to Embodiment 4 of the disclosure. 
         FIG. 16A  to  FIG. 16L  illustrate transverse aberration of the wide-angle lens according to Embodiment 4 of the disclosure. 
         FIG. 17  illustrates a wide-angle lens according to Embodiment 5 of the disclosure. 
         FIG. 18A  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 5 of the disclosure. 
         FIG. 18B  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 5 of the disclosure. 
         FIG. 19A  illustrates lateral chromatic aberration (transverse chromatic aberration) of the wide-angle lens according to Embodiment 5 of the disclosure. 
         FIG. 19B  illustrates spherical aberration (longitudinal aberration) of the wide-angle lens according to Embodiment 5 of the disclosure. 
         FIG. 20A  to  FIG. 20L  illustrate transverse aberration of the wide-angle lens according to Embodiment 5 of the disclosure. 
         FIG. 21  illustrates a wide-angle lens according to Embodiment 6 of the disclosure. 
         FIG. 22A  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 6 of the disclosure. 
         FIG. 22B  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 6 of the disclosure. 
         FIG. 23A  illustrates lateral chromatic aberration (transverse chromatic aberration) of the wide-angle lens according to Embodiment 6 of the disclosure. 
         FIG. 23B  illustrates spherical aberration (longitudinal aberration) of the wide-angle lens according to Embodiment 6 of the disclosure. 
         FIG. 24A  to  FIG. 24L  illustrate transverse aberration of the wide-angle lens according to Embodiment 6 of the disclosure. 
         FIG. 25  illustrates a wide-angle lens according to Embodiment 7 of the disclosure. 
         FIG. 26A  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 7 of the disclosure. 
         FIG. 26B  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 7 of the disclosure. 
         FIG. 27A  illustrates lateral chromatic aberration (transverse chromatic aberration) of the wide-angle lens according to Embodiment 7 of the disclosure. 
         FIG. 27B  illustrates spherical aberration (longitudinal aberration) of the wide-angle lens according to Embodiment 7 of the disclosure. 
         FIG. 28A  to  FIG. 28L  illustrate transverse aberration of the wide-angle lens according to Embodiment 7 of the disclosure. 
         FIG. 29  illustrates a wide-angle lens according to Embodiment 8 of the disclosure. 
         FIG. 30A  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 8 of the disclosure. 
         FIG. 30B  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 8 of the disclosure. 
         FIG. 31A  illustrates lateral chromatic aberration (transverse chromatic aberration) of the wide-angle lens according to Embodiment 8 of the disclosure. 
         FIG. 31B  illustrates spherical aberration (longitudinal aberration) of the wide-angle lens according to Embodiment 8 of the disclosure. 
         FIG. 32A  to  FIG. 32L  illustrate transverse aberration of the wide-angle lens according to Embodiment 8 of the disclosure. 
         FIG. 33  illustrates a wide-angle lens according to Embodiment 9 of the disclosure. 
         FIG. 34A  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 9 of the disclosure. 
         FIG. 34B  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 9 of the disclosure. 
         FIG. 35A  illustrates lateral chromatic aberration (transverse chromatic aberration) of the wide-angle lens according to Embodiment 9 of the disclosure. 
         FIG. 35B  illustrates spherical aberration (longitudinal aberration) of the wide-angle lens according to Embodiment 9 of the disclosure. 
         FIG. 36A  to  FIG. 36L  illustrate transverse aberration of the wide-angle lens according to Embodiment 9 of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, each embodiment of a wide-angle lens of the disclosure will be described with reference to the accompanying drawings. In the following description, in an extension direction of an optical axis L, an object side is denoted by L 1 , and an image side is denoted by L 2 . 
       FIG. 1  illustrates a wide-angle lens according to Embodiment 1 of the disclosure.  FIG. 2A  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 1 of the disclosure.  FIG. 2B  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 1 of the disclosure.  FIG. 3A  illustrates lateral chromatic aberration (transverse chromatic aberration) of the wide-angle lens according to Embodiment 1 of the disclosure.  FIG. 3B  illustrates spherical aberration (longitudinal aberration) of the wide-angle lens according to Embodiment 1 of the disclosure.  FIG. 4A  to  FIG. 4L  illustrate transverse aberration of the wide-angle lens according to Embodiment 1 of the disclosure. Here, in  FIG. 2A ,  FIG. 2B ,  FIG. 3A ,  FIG. 3B , and  FIG. 4A  to  FIG. 4L , a correlation curve of red light R (having a wavelength of 656 nm) is denoted by R, a correlation curve of green light G (having a wavelength of 588 nm) is denoted by G, and a correlation curve of blue light B (having a wavelength of 486 nm) is denoted by B. T indicates being related to the meridian plane, and S indicates being related to the sagittal plane. Moreover, in  FIG. 4A  to  FIG. 4L , a maximum scale of the longitudinal axis is ±50.000 μm. 
     As shown in  FIG. 1 , a wide-angle lens  1000  includes, sequentially arranged from the object side (L 1  side), a first lens  110 , a second lens  120 , a third lens  130 , a fourth lens  140 , a diaphragm  180 , a fifth lens  150 , a sixth lens  160  and a seventh lens  170 . Among them, the sixth lens  160  and the seventh lens  170  are bonded together by an adhesive to constitute a cemented lens. 
     Here, the first lens  110  is a lens (simply referred to as negative lens) with negative refractive power, having a convex surface (first surface  1 ) facing the object side L 1  and a concave surface (second surface  2 ) facing the image side L 2 . In this embodiment, the first lens  110  is a glass lens in which the first surface  1  and the second surface  2  are spherical surfaces. 
     The second lens  120  is a lens with negative refractive power, having a convex surface (third surface  3 ) facing the object side L 1  and a concave surface (fourth surface  4 ) facing the image side L 2 . In this embodiment, the second lens  120  is a plastic lens in which the third surface  3  and the fourth surface  4  are aspherical surfaces. 
     The third lens  130  is a lens (simply referred to as positive lens) with positive refractive power, having a concave surface (fifth surface  5 ) facing the object side L 1  and a convex surface (sixth surface  6 ) facing the image side L 2 . In this embodiment, the third lens  130  is a plastic lens in which the fifth surface  5  and the sixth surface  6  are aspherical surfaces. 
     The fourth lens  140  is a lens with positive refractive power, having a concave surface (seventh surface  7 ) facing the object side L 1  and a convex surface (eighth surface  8 ) facing the image side L 2 . In this embodiment, the fourth lens  140  is a plastic lens in which the seventh surface  7  and the eighth surface  8  are aspherical surfaces. 
     The fifth lens  150  is a lens with positive refractive power, having a convex surface (tenth surface  10 ) facing the object side L 1  and a convex surface (eleventh surface  11 ) facing the image side L 2 . In this embodiment, the fifth lens  150  is composed of a glass lens. 
     The sixth lens  160  is a lens with negative refractive power, having a concave surface (twelfth surface  12 ) facing the object side L 1  and a concave surface (thirteenth surface  13 ) facing the image side L 2 . The sixth lens  160  constitutes a cemented lens with the seventh lens  170 . In this embodiment, the sixth lens  160  is a plastic lens in which the twelfth surface  12  and the thirteenth surface  13  are aspherical surfaces. 
     The seventh lens  170  is a lens with positive refractive power, having a convex surface (thirteenth surface  13 ) facing the object side L 1  and a convex surface (fourteenth surface  14 ) facing the image side L 2 . In this embodiment, the seventh lens  170  is a plastic lens in which the thirteenth surface  13  and the fourteenth surface  14  are aspherical surfaces. 
     In addition, in this embodiment, as shown in  FIG. 1 , a light-shielding sheet  190  is provided between the second lens  120  and the third lens  130 , a filter  200  is arranged on the image side of the seventh lens  170 , and an imaging element  300  is arranged on the image side of the filter  200 . 
     In this embodiment, in the lens system as a whole, an effective focal length f is 1.023 mm, an object-to-image distance (total track) d is 13.611 mm, an F value (image space F/#) is 2.02, a maximum half field of view (HFOV) (maximum half field angle) is 115 degrees, and an entrance pupil diameter HEP is 0.507 mm. 
     Table 1 shows physical properties of each surface of the wide-angle lens  1000  of this embodiment. Table 2-1 and Table 2-2 show aspheric coefficients of each surface of the wide-angle lens  1000  of this embodiment. 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                   
                   
                   
                 Effective 
                 Effective 
                 Effective 
               
               
                   
                 Radius of 
                   
                   
                   
                 focal 
                 focal 
                 focal 
               
               
                 Surface 
                 curvature 
                 Thickness 
                 N d   
                 v d   
                 length 
                 length 
                 length 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 1  
                 11.420 
                 1.510 
                 1.871 
                 40.73 
                 −5.963 
                 −1.338 
                 3.148 
               
               
                 2  
                 3.350 
                 2.050 
               
               
                 3* 
                 40.687 
                 0.600 
                 1.544 
                 56.4 
                 −2.328 
               
               
                 4* 
                 1.222 
                 1.427 
               
               
                 5* 
                 −11.789 
                 0.689 
                 1.544 
                 56.4 
                 6.742 
                 3.122 
               
               
                 6* 
                 −2.855 
                 0.597 
               
               
                 7* 
                 −13.315 
                 0.778 
                 1.635 
                 23.9 
                 4.923 
               
               
                 8* 
                 −2.589 
                 −0.039 
               
               
                 9  
                 Infinite 
                 0.257 
               
               
                 (diaphragm) 
               
               
                 10  
                 15.150 
                 1.288 
                 1.697 
                 55.46 
                 3.175 
                   
                 3.740 
               
               
                 11  
                 −2.501 
                 0.101 
               
               
                 12*  
                 −5.143 
                 0.500 
                 1.635 
                 23.9 
                 −1.297 
                 13.449 
               
               
                 13*  
                 1.018 
                 2.362 
                 1.544 
                 56.4 
                 1.745 
               
               
                 14*  
                 −2.561 
                 0.965 
               
               
                 15  
                 Infinite 
                 0.400 
               
               
                 16  
                 Infinite 
                 0.125 
               
               
                   
               
            
           
         
       
     
     In Table 1 above, the radius of curvature, thickness, and effective focal length are in units of mm. N d  represents a refractive index for a ray of 587.56 nm. v d  represents the Abbe number. * represents an aspheric surface. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 2-1 
               
               
                   
               
               
                 Surface 
                 c (1/radius of curvature) 
                 K 
                 A4 
                 A6 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 3 
                  2.45778E−02 
                 0.00000E+00 
                 −7.34647E−04  
                 0.00000E+00 
               
               
                 4 
                  8.18649E−01 
                 −1.00000E+00  
                 3.34909E−02 
                 1.52429E−02 
               
               
                 5 
                 −8.48284E−02 
                 0.00000E+00 
                 −1.05901E−02  
                 2.28744E−02 
               
               
                 6 
                 −3.50286E−01 
                 0.00000E+00 
                 4.60516E−02 
                 1.35719E−02 
               
               
                 7 
                 −7.51052E−02 
                 0.00000E+00 
                 6.96916E−02 
                 5.26973E−04 
               
               
                 8 
                 −3.86206E−01 
                 0.00000E+00 
                 4.85130E−02 
                 1.07658E−02 
               
               
                 12 
                 −1.94439E−01 
                 0.00000E+00 
                 1.37213E−02 
                 −3.80723E−02  
               
               
                 13 
                  9.82404E−01 
                 −1.00000E+00  
                 2.47704E−01 
                 −2.97167E−01  
               
               
                 14 
                 −3.90445E−01 
                 0.00000E+00 
                 2.43790E−02 
                 −1.73998E−02  
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 2-2 
               
               
                   
               
               
                 Surface 
                 A8 
                 A10 
                 A12 
                 A14 
                 A16 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 3 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 4 
                 −3.29328E−03  
                 2.82298E−03 
                 −4.88754E−04  
                 0.00000E+00 
                 0.00000E+00 
               
               
                 5 
                 −5.12306E−03  
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 6 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 7 
                 4.37857E−03 
                 2.92148E−03 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 8 
                 −5.94177E−03  
                 1.11565E−02 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 12 
                 1.79956E−02 
                 −7.87537E−04  
                 −1.30556E−03  
                 0.00000E+00 
                 0.00000E+00 
               
               
                 13 
                 1.73181E−01 
                 −4.77496E−02  
                 4.65741E−03 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 14 
                 1.34046E−02 
                 −4.35536E−03  
                 5.73510E−04 
                 0.00000E+00 
                 0.00000E+00 
               
               
                   
               
            
           
         
       
     
     In Table 2-1 and Table 2-2 above, in a case where a lens surface is a convex surface protruding toward the object side or a concave surface recessed toward the object side, its radius of curvature is set to a positive value; in a case where a lens surface is a convex surface protruding toward the image side or a concave surface recessed toward the image side, its radius of curvature is set to a negative value. 
     In addition, Table 2-1 and Table 2-2 above show the aspheric coefficients A4, A6, A8, A10, A12, A14 and A16 of each of the aspheric surfaces, which satisfy the following expression (Expression 1). In the following expression, Z represents sag (axis in an optical axis direction), r represents height (ray height) in a direction perpendicular to the optical axis, K represents the conic coefficient, and c represents the reciprocal of the radius of curvature. 
     
       
         
           
             
               
                 
                   Z 
                   = 
                   
                     
                       
                         c 
                          
                         
                           r 
                           2 
                         
                       
                       
                         1 
                         + 
                         
                           
                             1 
                             - 
                             
                               
                                 ( 
                                 
                                   1 
                                   + 
                                   K 
                                 
                                 ) 
                               
                                
                               
                                 c 
                                 2 
                               
                                
                               
                                 r 
                                 2 
                               
                             
                           
                         
                       
                     
                     + 
                     
                       
                         ∑ 
                         
                           n 
                           = 
                           2 
                         
                         5 
                       
                        
                       
                         
                           A 
                           
                             2 
                              
                             n 
                           
                         
                          
                         
                           r 
                           
                             2 
                              
                             n 
                           
                         
                       
                     
                   
                 
               
               
                 
                   [ 
                   
                     Expression 
                      
                     
                         
                     
                      
                     1 
                   
                   ] 
                 
               
             
           
         
       
     
     Here, in the wide-angle lens  1000 , the object-to-image distance d is 13.611 mm, and the entrance pupil diameter HEP is 0.507 mm. Therefore, the following condition 1 is satisfied: 
         d/HEP&lt; 29.000  (1)
 
     In condition 1, if d/HEP is 29.000 or greater, it is difficult to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     In contrast, in this embodiment, since condition 1 is satisfied, it is easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     Particularly, in this embodiment, since d/HEP&lt;27.000 is satisfied, it is relatively easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     In addition, in the wide-angle lens  1000 , the object-to-image distance d is 13.611 mm, and the effective focal length f of the lens system as a whole is 1.023 mm. Therefore, the following condition 2 is satisfied: 
       11.000 &lt;d/f&lt; 15.000  (2)
 
     In condition 2, if d/f is 11.000 or less, it is difficult to appropriately correct various aberrations. On the other hand, if d/f is 15.000 or greater, the overall length of the lens system becomes excessively large. 
     In contrast, in this embodiment, since condition 2 is satisfied, it is easy to appropriately correct various aberrations, making it easy to achieve good optical characteristics. Moreover, it is possible to prevent the lens system from becoming excessively large while avoiding an excessively large overall length of the lens system. 
     In addition, in the wide-angle lens  1000 , the effective focal length f of the lens system as a whole is 1.023 mm, and the entrance pupil diameter HEP is 0.507 mm. Therefore, the following condition 3 is satisfied: 
         f/HEP&lt; 2.3  (3)
 
     In condition 3, if f/HEP is 2.3 or greater, it is difficult to ensure the brightness. 
     In contrast, in this embodiment, since condition 3 is satisfied, it is possible to ensure the brightness and to enable application in a high-density imaging element. 
     In addition, in the wide-angle lens  1000 , the combined effective focal length f1234 of the first lens  110 , the second lens  120 , the third lens  130 , and the fourth lens  140  is 3.148 mm, and the combined effective focal length f567 of the fifth lens  150 , the sixth lens  160 , and the seventh lens  170  is 3.740 mm. Therefore, the following condition 4 is satisfied: 
       0.800&lt; f 1234/ f 567&lt;8.000  (4)
 
     In condition 4, if f1234/f567 is 0.800 or less, the refractive power of the front lens group composed of the first lens, the second lens, the third lens, and the fourth lens is excessively high, making it difficult to appropriately correct various aberrations. On the other hand, if f1234/f567 is 8.000 or greater, the refractive power of the front lens group composed of the first lens, the second lens, the third lens, and the fourth lens is excessively low, making it difficult to reduce the diameter of each lens of the front lens group and to miniaturize the wide-angle lens as a whole. 
     In contrast, in this embodiment, since condition 4 is satisfied, it is easy to appropriately correct various aberrations and to realize miniaturization. 
     In addition, in the wide-angle lens  1000 , the combined effective focal length f567 of the fifth lens  150 , the sixth lens  160 , and the seventh lens  170  is 3.740 mm, and the effective focal length f of the lens system as a whole is 1.023 mm. Therefore, the following condition 5 is satisfied: 
       2.800 &lt;f 567 /f&lt; 3.850  (5)
 
     In condition 5, if f567/f is 2.800 or less, the refractive power of the rear lens group composed of the fifth lens, the sixth lens, and the seventh lens is excessively high, making it difficult to appropriately correct various aberrations, especially chromatic aberration. On the other hand, if f567/f is 3.850 or greater, it is difficult to reduce the diameter of each lens and the object-to-image distance, thus making it difficult to miniaturize the wide-angle lens as a whole. 
     In contrast, in this embodiment, since condition 5 is satisfied, it is easy to appropriately correct various aberrations, especially chromatic aberration, and to realize miniaturization. 
     In summary, in this embodiment, by configuring the wide-angle lens  1000  as above, as shown in  FIG. 2A  to  FIG. 4L , it is easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
       FIG. 5  illustrates a wide-angle lens according to Embodiment 2 of the disclosure.  FIG. 6A  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 2 of the disclosure.  FIG. 6B  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 2 of the disclosure.  FIG. 7A  illustrates lateral chromatic aberration (transverse chromatic aberration) of the wide-angle lens according to Embodiment 2 of the disclosure.  FIG. 7B  illustrates spherical aberration (longitudinal aberration) of the wide-angle lens according to Embodiment 2 of the disclosure.  FIG. 8A  to  FIG. 8L  illustrate transverse aberration of the wide-angle lens according to Embodiment 2 of the disclosure. Here, in  FIG. 6A ,  FIG. 6B ,  FIG. 7A ,  FIG. 7B , and  FIG. 8A  to  FIG. 8L , a correlation curve of red light R (having a wavelength of 656 nm) is denoted by R, a correlation curve of green light G (having a wavelength of 588 nm) is denoted by G, and a correlation curve of blue light B (having a wavelength of 486 nm) is denoted by B. T indicates being related to the meridian plane, and S indicates being related to the sagittal plane. Moreover, in  FIG. 8A  to  FIG. 8L , the maximum scale of the longitudinal axis is ±50.000 μm. 
     As shown in  FIG. 5 , the wide-angle lens  1000  includes, sequentially arranged from the object side (L 1  side), the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , the diaphragm  180 , the fifth lens  150 , the sixth lens  160  and the seventh lens  170 . Among them, the sixth lens  160  and the seventh lens  170  are bonded together by an adhesive to constitute a cemented lens. 
     Here, the wide-angle lens  1000  in this embodiment has the same basic structure (that is, whether each of the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , the fifth lens  150 , the sixth lens  160  and the seventh lens  170  has positive refractive power or negative refractive power, whether each of these lenses is a glass lens or plastic lens, whether the object side surface and the image side surface of each of these lenses are convex surfaces or concave surfaces, and whether the object side surface and the image side surface are spherical surfaces or aspheric surfaces) as that of the wide-angle lens of Embodiment 1, and thus the details thereof will be omitted. 
     In addition, as shown in  FIG. 5 , similarly to Embodiment 1, the light-shielding sheet  190  is provided between the second lens  120  and the third lens  130 , the filter  200  is arranged on the image side of the seventh lens  170 , and the imaging element  300  is arranged on the image side of the filter  200 . 
     In this embodiment, in the lens system as a whole, the effective focal length f is 1.062 mm, the object-to-image distance (total track) d is 13.610 mm, the F value (image space F/#) is 2.02, the maximum HFOV (maximum half field angle) is 115 degrees, and the entrance pupil diameter HEP is 0.526 mm. 
     Table 3 shows physical properties of each surface of the wide-angle lens  1000  of this embodiment. Table 4-1 and Table 4-2 show aspheric coefficients of each surface of the wide-angle lens  1000  of this embodiment. 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                 TABLE 3 
               
               
                   
               
               
                   
                   
                   
                   
                   
                 Effective 
                 Effective 
                 Effective 
               
               
                   
                 Radius of 
                   
                   
                   
                 focal 
                 focal 
                 focal 
               
               
                 Surface 
                 curvature 
                 Thickness 
                 N d   
                 v d   
                 length 
                 length 
                 length 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 1  
                 11.363 
                 1.561 
                 1.871 
                 40.73 
                 −5.895 
                 −1.406 
                 4.237 
               
               
                 2  
                 3.310 
                 2.024 
               
               
                 3* 
                 45.562 
                 0.600 
                 1.544 
                 56.4 
                 −2.489 
               
               
                 4* 
                 1.309 
                 1.360 
               
               
                 5* 
                 −9.695 
                 0.703 
                 1.544 
                 56.4 
                 6.297 
                 3.380 
               
               
                 6* 
                 −2.596 
                 0.565 
               
               
                 7* 
                 −4.818 
                 0.732 
                 1.635 
                 23.9 
                 5.955 
               
               
                 8* 
                 −2.244 
                 −0.043 
               
               
                 9  
                 Infinite 
                 0.201 
               
               
                 (diaphragm) 
               
               
                 10  
                 16.738 
                 1.245 
                 1.697 
                 55.46 
                 3.436 
                   
                 3.640 
               
               
                 11  
                 −2.709 
                 0.244 
               
               
                 12*  
                 −6.978 
                 0.500 
                 1.635 
                 23.9 
                 −1.379 
                 8.893 
               
               
                 13*  
                 1.029 
                 2.426 
                 1.544 
                 56.4 
                 1.765 
               
               
                 14*  
                 −2.427 
                 0.968 
               
               
                 15  
                 Infinite 
                 0.400 
               
               
                 16  
                 Infinite 
                 0.125 
               
               
                   
               
            
           
         
       
     
     In Table 3 above, the radius of curvature, thickness, and effective focal length are in units of mm. N d  represents a refractive index for a ray of 587.56 nm. v d  represents the Abbe number. * represents an aspheric surface. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 4-1 
               
               
                   
               
               
                 Surface 
                 c (1/radius of curvature) 
                 K 
                 A4 
                 A6 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 3 
                  2.19479E−02 
                 0.00000E+00 
                 −5.53459E−04  
                  0.00000E+00 
               
               
                 4 
                  7.64121E−01 
                 −1.00000E+00  
                 4.76939E−02 
                  1.87020E−03 
               
               
                 5 
                 −1.03144E−01 
                 0.00000E+00 
                 −4.63672E−04  
                  2.39479E−02 
               
               
                 6 
                 −3.85243E−01 
                 0.00000E+00 
                 6.19526E−02 
                  9.41258E−03 
               
               
                 7 
                 −2.07563E−01 
                 0.00000E+00 
                 8.01905E−02 
                 −1.81445E−02 
               
               
                 8 
                 −4.45687E−01 
                 0.00000E+00 
                 5.32792E−02 
                 −3.21513E−03 
               
               
                 12 
                 −1.43308E−01 
                 0.00000E+00 
                 2.59200E−02 
                 −4.54679E−02 
               
               
                 13 
                  9.71678E−01 
                 −1.00000E+00  
                 2.67381E−01 
                 −3.18917E−01 
               
               
                 14 
                 −4.11994E−01 
                 0.00000E+00 
                 2.93182E−02 
                 −2.05884E−02 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 4-2 
               
               
                   
               
               
                 Surface 
                 A8 
                 A10 
                 A12 
                 A14 
                 A16 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 3 
                 0.00000E+00 
                  0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 4 
                 1.18832E−02 
                 −3.21383E−03 
                 7.23623E-04 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 5 
                 −7.11892E−03  
                  0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 6 
                 0.00000E+00 
                  0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 7 
                 1.48329E−02 
                 −9.20347E−04 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 8 
                 3.16264E−03 
                  4.17741E−03 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 12 
                 −7.44565E−04  
                 −1.42901E−03 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 13 
                 1.80337E−01 
                 −4.80759E−02 
                 4.57265E−03 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 14 
                 1.50208E−02 
                 −4.69107E−03 
                 5.90742E−04 
                 0.00000E+00 
                 0.00000E+00 
               
               
                   
               
            
           
         
       
     
     In Table 4-1 and Table 4-2 above, in a case where a lens surface is a convex surface protruding toward the object side or a concave surface recessed toward the object side, its radius of curvature is set to a positive value; in a case where a lens surface is a convex surface protruding toward the image side or a concave surface recessed toward the image side, its radius of curvature is set to a negative value. 
     In addition, Table 4-1 and Table 4-2 above show the aspheric coefficients A4, A6, A8, A10, A12, A14 and A16 of each of the aspheric surfaces, which satisfy Expression 1 above. 
     Here, in the wide-angle lens  1000 , the object-to-image distance d is 13.610 mm, and the entrance pupil diameter HEP is 0.526 mm. Therefore, the following condition 1 is satisfied: 
         d/HEP&lt; 29.000  (1)
 
     In condition 1, if d/HEP is 29.000 or greater, it is difficult to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     In contrast, in this embodiment, since condition 1 is satisfied, it is easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     Particularly, in this embodiment, since d/HEP&lt;27.000 is satisfied, it is relatively easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     In addition, in the wide-angle lens  1000 , the object-to-image distance d is 13.610 mm, and the effective focal length f of the lens system as a whole is 1.062 mm. Therefore, the following condition 2 is satisfied: 
       11.000 &lt;d/f&lt; 15.000  (2)
 
     In condition 2, if d/f is 11.000 or less, it is difficult to appropriately correct various aberrations. On the other hand, if d/f is 15.000 or greater, the overall length of the lens system becomes excessively large. 
     In contrast, in this embodiment, since condition 2 is satisfied, it is easy to appropriately correct various aberrations, making it easy to achieve good optical characteristics. Moreover, it is possible to prevent the lens system from becoming excessively large while avoiding an excessively large overall length of the lens system. 
     In addition, in the wide-angle lens  1000 , the effective focal length f of the lens system as a whole is 1.062 mm, and the entrance pupil diameter HEP is 0.526 mm. Therefore, the following condition 3 is satisfied: 
         f/HEP&lt; 2.3  (3)
 
     In condition 3, if f/HEP is 2.3 or greater, it is difficult to ensure the brightness. 
     In contrast, in this embodiment, since condition 3 is satisfied, it is possible to ensure the brightness and to enable application in a high-density imaging element. 
     In addition, in the wide-angle lens  1000 , the combined effective focal length f1234 of the first lens  110 , the second lens  120 , the third lens  130 , and the fourth lens  140  is 4.237 mm, and the combined effective focal length f567 of the fifth lens  150 , the sixth lens  160 , and the seventh lens  170  is 3.640 mm. Therefore, the following condition 4 is satisfied: 
       0.800 &lt;f 1234 /f 4567&lt;8.000  (4)
 
     In condition 4, if f1234/f567 is 0.800 or less, the refractive power of the front lens group composed of the first lens, the second lens, the third lens, and the fourth lens is excessively high, making it difficult to appropriately correct various aberrations. On the other hand, if f1234/f567 is 8.000 or greater, the refractive power of the front lens group composed of the first lens, the second lens, the third lens, and the fourth lens is excessively low, making it difficult to reduce the diameter of each lens of the front lens group and to miniaturize the wide-angle lens as a whole. 
     In contrast, in this embodiment, since condition 4 is satisfied, it is easy to appropriately correct various aberrations and to realize miniaturization. 
     In addition, in the wide-angle lens  1000 , the combined effective focal length f567 of the fifth lens  150 , the sixth lens  160 , and the seventh lens  170  is 3.640 mm, and the effective focal length f of the lens system as a whole is 1.062 mm. Therefore, the following condition 5 is satisfied: 
       2.800 &lt;f 567 /f&lt; 3.850  (5)
 
     In condition 5, if f567/f is 2.800 or less, the refractive power of the rear lens group composed of the fifth lens, the sixth lens, and the seventh lens is excessively high, making it difficult to appropriately correct various aberrations, especially chromatic aberration. On the other hand, if f567/f is 3.850 or greater, it is difficult to reduce the diameter of each lens and the object-to-image distance, thus making it difficult to miniaturize the wide-angle lens as a whole. 
     In contrast, in this embodiment, since condition 5 is satisfied, it is easy to appropriately correct various aberrations, especially chromatic aberration, and to realize miniaturization. 
     In summary, in this embodiment, by configuring the wide-angle lens  1000  as above, as shown in  FIG. 6A  to  FIG. 8L , it is easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
       FIG. 9  illustrates a wide-angle lens according to Embodiment 3 of the disclosure.  FIG. 10A  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 3 of the disclosure.  FIG. 10B  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 3 of the disclosure.  FIG. 11A  illustrates lateral chromatic aberration (transverse chromatic aberration) of the wide-angle lens according to Embodiment 3 of the disclosure.  FIG. 11B  illustrates spherical aberration (longitudinal aberration) of the wide-angle lens according to Embodiment 3 of the disclosure.  FIG. 12A  to  FIG. 12L  illustrate transverse aberration of the wide-angle lens according to Embodiment 3 of the disclosure. Here, in  FIG. 10A ,  FIG. 10B ,  FIG. 11A ,  FIG. 11B , and  FIG. 12A  to  FIG. 12L , a correlation curve of red light R (having a wavelength of 656 nm) is denoted by R, a correlation curve of green light G (having a wavelength of 588 nm) is denoted by G, and a correlation curve of blue light B (having a wavelength of 486 nm) is denoted by B. T indicates being related to the meridian plane, and S indicates being related to the sagittal plane. Moreover, in  FIG. 12A  to  FIG. 12L , the maximum scale of the longitudinal axis is ±50.000 μm. 
     As shown in  FIG. 9 , the wide-angle lens  1000  includes, sequentially arranged from the object side (L 1  side), the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , the diaphragm  180 , the fifth lens  150 , the sixth lens  160  and the seventh lens  170 . Among them, the sixth lens  160  and the seventh lens  170  are bonded together by an adhesive to constitute a cemented lens. 
     Here, the wide-angle lens  1000  in this embodiment has the same basic structure (that is, whether each of the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , the fifth lens  150 , the sixth lens  160  and the seventh lens  170  has positive refractive power or negative refractive power, whether each of these lenses is a glass lens or plastic lens, whether the object side surface and the image side surface of each of these lenses are convex surfaces or concave surfaces, and whether the object side surface and the image side surface are spherical surfaces or aspheric surfaces) as that of the wide-angle lens of Embodiment 1, and thus the details thereof will be omitted. 
     In addition, as shown in  FIG. 9 , similarly to Embodiment 1, the light-shielding sheet  190  is provided between the second lens  120  and the third lens  130 , the filter  200  is arranged on the image side of the seventh lens  170 , and the imaging element  300  is arranged on the image side of the filter  200 . 
     In this embodiment, in the lens system as a whole, the effective focal length f is 1.026 mm, the object-to-image distance (total track) d is 13.403 mm, the F value (image space F/#) is 2.02, the maximum HFOV (maximum half field angle) is 109 degrees, and the entrance pupil diameter HEP is 0.508 mm. 
     Table 5 shows physical properties of each surface of the wide-angle lens  1000  of this embodiment. Table 6-1 and Table 6-2 show aspheric coefficients of each surface of the wide-angle lens  1000  of this embodiment. 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                 TABLE 5 
               
               
                   
               
               
                   
                   
                   
                   
                   
                 Effective 
                 Effective 
                 Effective 
               
               
                   
                 Radius of 
                   
                   
                   
                 focal 
                 focal 
                 focal 
               
               
                 Surface 
                 curvature 
                 Thickness 
                 N d   
                 v d   
                 length 
                 length 
                 length 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 1  
                 11.171 
                 1.300 
                 1.871 
                 40.73 
                 −5.584 
                 −1.467 
                 3.572 
               
               
                 2  
                 3.204 
                 1.815 
               
               
                 3* 
                 35.057 
                 0.600 
                 1.544 
                 56.4 
                 −2.673 
               
               
                 4* 
                 1.388 
                 1.422 
               
               
                 5* 
                 −5.882 
                 0.763 
                 1.544 
                 56.4 
                 7.039 
                 3.456 
               
               
                 6* 
                 −2.425 
                 0.839 
               
               
                 7* 
                 −6.368 
                 0.718 
                 1.635 
                 23.9 
                 5.655 
               
               
                 8* 
                 −2.397 
                 −0.037 
               
               
                 9  
                 Infinite 
                 0.347 
               
               
                 (diaphragm) 
               
               
                 10  
                 7.103 
                 1.300 
                 1.697 
                 55.46 
                 3.076 
                   
                 3.663 
               
               
                 11  
                 −2.839 
                 0.135 
               
               
                 12*  
                 −4.077 
                 0.500 
                 1.635 
                 23.9 
                 −1.284 
                 11.542 
               
               
                 13*  
                 1.068 
                 2.213 
                 1.544 
                 56.4 
                 1.744 
               
               
                 14*  
                 −2.294 
                 0.963 
               
               
                 15  
                 Infinite 
                 0.400 
               
               
                 16  
                 Infinite 
                 0.125 
               
               
                   
               
            
           
         
       
     
     In Table 5 above, the radius of curvature, thickness, and effective focal length are in units of mm. N d  represents a refractive index for a ray of 587.56 nm. v d  represents the Abbe number. * represents an aspheric surface. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 6-1 
               
               
                   
               
               
                 Surface 
                 c (1/radius of curvature) 
                 K 
                 A4 
                 A6 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 3 
                  2.85248E−02 
                 0.00000E+00 
                 −7.73953E−04  
                 −2.76248E−05 
               
               
                 4 
                  7.20578E−01 
                 −1.00000E+00  
                 1.69157E−02 
                  2.83585E−02 
               
               
                 5 
                 −1.69997E−01 
                 0.00000E+00 
                 4.77013E−03 
                  1.28269E−02 
               
               
                 6 
                 −4.12314E−01 
                 0.00000E+00 
                 4.38590E−02 
                  3.36563E−03 
               
               
                 7 
                 −1.57044E−01 
                 0.00000E+00 
                 5.20793E−02 
                 −9.74604E−03 
               
               
                 8 
                 −4.17218E−01 
                 0.00000E+00 
                 3.75209E−02 
                 −1.18387E−03 
               
               
                 12 
                 −2.45256E−01 
                 0.00000E+00 
                 1.12258E−02 
                 −2.18878E−02 
               
               
                 13 
                  9.36158E−01 
                 −1.00000E+00  
                 1.84892E−01 
                 −2.17248E−01 
               
               
                 14 
                 −4.35910E−01 
                 0.00000E+00 
                 6.08264E−02 
                 −6.37284E−02 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 6-2 
               
               
                   
               
               
                 Surface 
                 A8 
                 A10 
                 A12 
                 A14 
                 A16 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 3 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 4 
                 −1.08170E−02  
                 3.74135E−03 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 5 
                 −6.95368E−04  
                 2.73435E−05 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 6 
                 2.29705E−03 
                 −1.23857E−05  
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 7 
                 8.85677E−03 
                 −7.73714E−05  
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 8 
                 4.43504E−03 
                 9.66329E−04 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 12 
                 3.37862E−04 
                 9.82658E−03 
                 −3.53648E−03  
                 −1.65685E−04  
                 0.00000E+00 
               
               
                 13 
                 1.49413E−01 
                 −7.49877E−02  
                 2.96657E−02 
                 −5.71297E−03  
                 0.00000E+00 
               
               
                 14 
                 5.78846E−02 
                 −2.66940E−02  
                 6.28648E−03 
                 −5.86821E−04  
                 0.00000E+00 
               
               
                   
               
            
           
         
       
     
     In Table 6-1 and Table 6-2 above, in a case where a lens surface is a convex surface protruding toward the object side or a concave surface recessed toward the object side, its radius of curvature is set to a positive value; in a case where a lens surface is a convex surface protruding toward the image side or a concave surface recessed toward the image side, its radius of curvature is set to a negative value. 
     In addition, Table 6-1 and Table 6-2 above show the aspheric coefficients A4, A6, A8, A10, A12, A14 and A16 of each of the aspheric surfaces, which satisfy Expression 1 above. 
     Here, in the wide-angle lens  1000 , the object-to-image distance d is 13.403 mm, and the entrance pupil diameter HEP is 0.508 mm. Therefore, the following condition 1 is satisfied: 
         d/HEP&lt; 29.000  (1)
 
     In condition 1, if d/HEP is 29.000 or greater, it is difficult to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     In contrast, in this embodiment, since condition 1 is satisfied, it is easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     Particularly, in this embodiment, since d/HEP&lt;27.000 is satisfied, it is relatively easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     In addition, in the wide-angle lens  1000 , the object-to-image distance d is 13.403 mm, and the effective focal length f of the lens system as a whole is 1.026 mm. Therefore, the following condition 2 is satisfied: 
       11.000 &lt;d/f&lt; 15.000  (2)
 
     In condition 2, if d/f is 11.000 or less, it is difficult to appropriately correct various aberrations. On the other hand, if d/f is 15.000 or greater, the overall length of the lens system becomes excessively large. 
     In contrast, in this embodiment, since condition 2 is satisfied, it is easy to appropriately correct various aberrations, making it easy to achieve good optical characteristics. Moreover, it is possible to prevent the lens system from becoming excessively large while avoiding an excessively large overall length of the lens system. 
     In addition, in the wide-angle lens  1000 , the effective focal length f of the lens system as a whole is 1.026 mm, and the entrance pupil diameter HEP is 0.508 mm. Therefore, the following condition 3 is satisfied: 
         f/HEP&lt; 2.3  (3)
 
     In condition 3, if f/HEP is 2.3 or greater, it is difficult to ensure the brightness. 
     In contrast, in this embodiment, since condition 3 is satisfied, it is possible to ensure the brightness and to enable application in a high-density imaging element. 
     In addition, in the wide-angle lens  1000 , the combined effective focal length f1234 of the first lens  110 , the second lens  120 , the third lens  130 , and the fourth lens  140  is 3.572 mm, and the combined effective focal length f567 of the fifth lens  150 , the sixth lens  160 , and the seventh lens  170  is 3.663 mm. Therefore, the following condition 4 is satisfied: 
       0.800 &lt;f 1234 /f 4567&lt;8.000  (4)
 
     In condition 4, if f1234/f567 is 0.800 or less, the refractive power of the front lens group composed of the first lens, the second lens, the third lens, and the fourth lens is excessively high, making it difficult to appropriately correct various aberrations. On the other hand, if f1234/f567 is 8.000 or greater, the refractive power of the front lens group composed of the first lens, the second lens, the third lens, and the fourth lens is excessively low, making it difficult to reduce the diameter of each lens of the front lens group and to miniaturize the wide-angle lens as a whole. 
     In contrast, in this embodiment, since condition 4 is satisfied, it is easy to appropriately correct various aberrations and to realize miniaturization. 
     In addition, in the wide-angle lens  1000 , the combined effective focal length f567 of the fifth lens  150 , the sixth lens  160 , and the seventh lens  170  is 3.663 mm, and the effective focal length f of the lens system as a whole is 1.026 mm. Therefore, the following condition 5 is satisfied: 
       2.800 &lt;f 567 /f&lt; 3.850  (5)
 
     In condition 5, if f567/f is 2.800 or less, the refractive power of the rear lens group composed of the fifth lens, the sixth lens, and the seventh lens is excessively high, making it difficult to appropriately correct various aberrations, especially chromatic aberration. On the other hand, if f567/f is 3.850 or greater, it is difficult to reduce the diameter of each lens and the object-to-image distance, thus making it difficult to miniaturize the wide-angle lens as a whole. 
     In contrast, in this embodiment, since condition 5 is satisfied, it is easy to appropriately correct various aberrations, especially chromatic aberration, and to realize miniaturization. 
     In summary, in this embodiment, by configuring the wide-angle lens  1000  as above, as shown in  FIG. 10A  to  FIG. 12L , it is easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
       FIG. 13  illustrates a wide-angle lens according to Embodiment 4 of the disclosure.  FIG. 14A  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 4 of the disclosure.  FIG. 14B  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 4 of the disclosure.  FIG. 15A  illustrates lateral chromatic aberration (transverse chromatic aberration) of the wide-angle lens according to Embodiment 4 of the disclosure.  FIG. 15B  illustrates spherical aberration (longitudinal aberration) of the wide-angle lens according to Embodiment 4 of the disclosure.  FIG. 16A  to  FIG. 16L  illustrate transverse aberration of the wide-angle lens according to Embodiment 4 of the disclosure. Here, in  FIG. 14A ,  FIG. 14B ,  FIG. 15A ,  FIG. 15B , and  FIG. 16A  to  FIG. 16L , a correlation curve of red light R (having a wavelength of 656 nm) is denoted by R, a correlation curve of green light G (having a wavelength of 588 nm) is denoted by G, and a correlation curve of blue light B (having a wavelength of 486 nm) is denoted by B. T indicates being related to the meridian plane, and S indicates being related to the sagittal plane. Moreover, in  FIG. 16A  to  FIG. 16L , the maximum scale of the longitudinal axis is ±50.000 μm. 
     As shown in  FIG. 13 , the wide-angle lens  1000  includes, sequentially arranged from the object side (L 1  side), the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , the diaphragm  180 , the fifth lens  150 , the sixth lens  160  and the seventh lens  170 . Among them, the sixth lens  160  and the seventh lens  170  are bonded together by an adhesive to constitute a cemented lens. 
     Here, the wide-angle lens  1000  in this embodiment has the same basic structure (that is, whether each of the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , the fifth lens  150 , the sixth lens  160  and the seventh lens  170  has positive refractive power or negative refractive power, whether each of these lenses is a glass lens or plastic lens, whether the object side surface and the image side surface of each of these lenses are convex surfaces or concave surfaces, and whether the object side surface and the image side surface are spherical surfaces or aspheric surfaces) as that of the wide-angle lens of Embodiment 1, and thus the details thereof will be omitted. 
     In addition, as shown in  FIG. 13 , similarly to Embodiment 1, the light-shielding sheet  190  is provided between the second lens  120  and the third lens  130 , the filter  200  is arranged on the image side of the seventh lens  170 , and the imaging element  300  is arranged on the image side of the filter  200 . 
     In this embodiment, in the lens system as a whole, the effective focal length f is 1.011 mm, the object-to-image distance (total track) d is 13.404 mm, the F value (image space F/#) is 2.03, the maximum HFOV (maximum half field angle) is 109 degrees, and the entrance pupil diameter HEP is 0.498 mm. 
     Table 7 shows physical properties of each surface of the wide-angle lens  1000  of this embodiment. Table 8-1 and Table 8-2 show aspheric coefficients of each surface of the wide-angle lens  1000  of this embodiment. 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                 TABLE 7 
               
               
                   
               
               
                   
                   
                   
                   
                   
                 Effective 
                 Effective 
                 Effective 
               
               
                   
                 Radius of 
                   
                   
                   
                 focal 
                 focal 
                 focal 
               
               
                 Surface 
                 curvature 
                 Thickness 
                 N d   
                 v d   
                 length 
                 length 
                 length 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 1  
                 11.850 
                 1.800 
                 1.871 
                 40.73 
                 −4.888 
                 −1.347 
                 6.571 
               
               
                 2  
                 2.910 
                 1.717 
               
               
                 3* 
                 23.043 
                 0.600 
                 1.544 
                 56.4 
                 −2.540 
               
               
                 4* 
                 1.291 
                 1.276 
               
               
                 5* 
                 −13.541 
                 0.750 
                 1.544 
                 56.4 
                 7.736 
                 3.614 
               
               
                 6* 
                 −3.273 
                 0.679 
               
               
                 7* 
                 −20.063 
                 0.710 
                 1.635 
                 23.9 
                 5.873 
               
               
                 8* 
                 −3.188 
                 0.056 
               
               
                 9  
                 Infinite 
                 0.076 
               
               
                 (diaphragm) 
               
               
                 10  
                 7.740 
                 1.320 
                 1.697 
                 55.46 
                 2.821 
                   
                 3.355 
               
               
                 11  
                 −2.450 
                 0.271 
               
               
                 12*  
                 −4.136 
                 0.500 
                 1.635 
                 23.9 
                 −1.168 
                 8.497 
               
               
                 13*  
                 0.946 
                 2.180 
                 1.544 
                 56.4 
                 1.601 
               
               
                 14*  
                 −2.056 
                 0.944 
               
               
                 15  
                 Infinite 
                 0.400 
               
               
                 16  
                 Infinite 
                 0.125 
               
               
                   
               
            
           
         
       
     
     In Table 7 above, the radius of curvature, thickness, and effective focal length are in units of mm. N d  represents a refractive index for a ray of 587.56 nm. v d  represents the Abbe number. * represents an aspheric surface. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 8-1 
               
               
                   
               
               
                 Surface 
                 c (1/radius of curvature) 
                 K 
                 A4 
                 A6 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 3 
                  4.33971E−02 
                 0.00000E+00 
                 −6.82448E−03  
                  3.73911E−03 
               
               
                 4 
                  7.74346E−01 
                 −5.39587E+00  
                 2.32631E−01 
                 −1.17492E−01 
               
               
                 5 
                 −7.38477E−02 
                 0.00000E+00 
                 2.29113E−02 
                  4.37979E−03 
               
               
                 6 
                 −3.05528E−01 
                 0.00000E+00 
                 4.74057E−02 
                 −5.28192E−03 
               
               
                 7 
                 −4.98442E−02 
                 0.00000E+00 
                 4.27102E−02 
                 −4.22032E−04 
               
               
                 8 
                 −3.13660E−01 
                 0.00000E+00 
                 3.38907E−02 
                  3.26534E−03 
               
               
                 12 
                 −2.41789E−01 
                 0.00000E+00 
                 −3.09436E−02  
                  3.41185E−02 
               
               
                 13 
                  1.05668E+00 
                 −1.00000E+00  
                 5.66189E−04 
                 −1.14232E−02 
               
               
                 14 
                 −4.86390E−01 
                 0.00000E+00 
                 7.16605E−02 
                 −6.17165E−02 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 8-2 
               
               
                   
               
               
                 Surface 
                 A8 
                 A10 
                 A12 
                 A14 
                 A16 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 3 
                 −1.15147E−03  
                  1.50789E−04 
                 −7.30801E−06  
                 0.00000E+00 
                 0.00000E+00 
               
               
                 4 
                 7.01048E−02 
                 −7.98133E−03 
                 −4.17335E−03  
                 0.00000E+00 
                 0.00000E+00 
               
               
                 5 
                 1.21716E−02 
                 −8.91664E−03 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 6 
                 2.05279E−02 
                 −2.11693E−02 
                 5.41203E−03 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 7 
                 6.15517E−03 
                  0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 8 
                 8.49340E−03 
                  3.83965E−03 
                 −2.61241E−03  
                 0.00000E+00 
                 0.00000E+00 
               
               
                 12 
                 −5.25642E−02  
                  5.03801E−02 
                 −2.60337E−02  
                 5.67639E−03 
                 0.00000E+00 
               
               
                 13 
                 1.93193E−02 
                 −2.02628E−02 
                 1.27147E−02 
                 −3.03203E−03  
                 0.00000E+00 
               
               
                 14 
                 5.37377E−02 
                 −2.41958E−02 
                 5.72598E−03 
                 −5.29799E−04  
                 0.00000E+00 
               
               
                   
               
            
           
         
       
     
     In Table 8-1 and Table 8-2 above, in a case where a lens surface is a convex surface protruding toward the object side or a concave surface recessed toward the object side, its radius of curvature is set to a positive value; in a case where a lens surface is a convex surface protruding toward the image side or a concave surface recessed toward the image side, its radius of curvature is set to a negative value. 
     In addition, Table 8-1 and Table 8-2 above show the aspheric coefficients A4, A6, A8, A10, A12, A14 and A16 of each of the aspheric surfaces, which satisfy Expression 1 above. 
     Here, in the wide-angle lens  1000 , the object-to-image distance d is 13.404 mm, and the entrance pupil diameter HEP is 0.498 mm. Therefore, the following condition 1 is satisfied: 
         d/HEP&lt; 29.000  (1)
 
     In condition 1, if d/HEP is 29.000 or greater, it is difficult to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     In contrast, in this embodiment, since condition 1 is satisfied, it is easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     Particularly, in this embodiment, since d/HEP&lt;27.000 is satisfied, it is relatively easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     In addition, in the wide-angle lens  1000 , the object-to-image distance d is 13.404 mm, and the effective focal length f of the lens system as a whole is 1.011 mm. Therefore, the following condition 2 is satisfied: 
       11.000 &lt;d/f&lt; 15.000  (2)
 
     In condition 2, if d/f is 11.000 or less, it is difficult to appropriately correct various aberrations. On the other hand, if d/f is 15.000 or greater, the overall length of the lens system becomes excessively large. 
     In contrast, in this embodiment, since condition 2 is satisfied, it is easy to appropriately correct various aberrations, making it easy to achieve good optical characteristics. Moreover, it is possible to prevent the lens system from becoming excessively large while avoiding an excessively large overall length of the lens system. 
     In addition, in the wide-angle lens  1000 , the effective focal length f of the lens system as a whole is 1.011 mm, and the entrance pupil diameter HEP is 0.498 mm. Therefore, the following condition 3 is satisfied: 
         f/HEP&lt; 2.3  (3)
 
     In condition 3, if f/HEP is 2.3 or greater, it is difficult to ensure the brightness. 
     In contrast, in this embodiment, since condition 3 is satisfied, it is possible to ensure the brightness and to enable application in a high-density imaging element. 
     In addition, in the wide-angle lens  1000 , the combined effective focal length f1234 of the first lens  110 , the second lens  120 , the third lens  130 , and the fourth lens  140  is 6.571 mm, and the combined effective focal length f567 of the fifth lens  150 , the sixth lens  160 , and the seventh lens  170  is 3.355 mm. Therefore, the following condition 4 is satisfied: 
       0.800 &lt;f 1234 /f 4567&lt;8.000  (4)
 
     In condition 4, if f1234/f567 is 0.800 or less, the refractive power of the front lens group composed of the first lens, the second lens, the third lens, and the fourth lens is excessively high, making it difficult to appropriately correct various aberrations. On the other hand, if f1234/f567 is 8.000 or greater, the refractive power of the front lens group composed of the first lens, the second lens, the third lens, and the fourth lens is excessively low, making it difficult to reduce the diameter of each lens of the front lens group and to miniaturize the wide-angle lens as a whole. 
     In contrast, in this embodiment, since condition 4 is satisfied, it is easy to appropriately correct various aberrations and to realize miniaturization. 
     In addition, in the wide-angle lens  1000 , the combined effective focal length f567 of the fifth lens  150 , the sixth lens  160 , and the seventh lens  170  is 3.355 mm, and the effective focal length f of the lens system as a whole is 1.011 mm. Therefore, the following condition 5 is satisfied: 
       2.800 &lt;f 567 /f&lt; 3.850  (5)
 
     In condition 5, if f567/f is 2.800 or less, the refractive power of the rear lens group composed of the fifth lens, the sixth lens, and the seventh lens is excessively high, making it difficult to appropriately correct various aberrations, especially chromatic aberration. On the other hand, if f567/f is 3.850 or greater, it is difficult to reduce the diameter of each lens and the object-to-image distance, thus making it difficult to miniaturize the wide-angle lens as a whole. 
     In contrast, in this embodiment, since condition 5 is satisfied, it is easy to appropriately correct various aberrations, especially chromatic aberration, and to realize miniaturization. 
     In summary, in this embodiment, by configuring the wide-angle lens  1000  as above, as shown in  FIG. 14A  to  FIG. 16L , it is easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
       FIG. 17  illustrates a wide-angle lens according to Embodiment 5 of the disclosure.  FIG. 18A  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 5 of the disclosure.  FIG. 18B  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 5 of the disclosure.  FIG. 19A  illustrates lateral chromatic aberration (transverse chromatic aberration) of the wide-angle lens according to Embodiment 5 of the disclosure.  FIG. 19B  illustrates spherical aberration (longitudinal aberration) of the wide-angle lens according to Embodiment 5 of the disclosure.  FIG. 20A  to  FIG. 20L  illustrate transverse aberration of the wide-angle lens according to Embodiment 5 of the disclosure. Here, in  FIG. 18A ,  FIG. 18B ,  FIG. 19A ,  FIG. 19B , and  FIG. 20A  to  FIG. 20L , a correlation curve of red light R (having a wavelength of 656 nm) is denoted by R, a correlation curve of green light G (having a wavelength of 588 nm) is denoted by G, and a correlation curve of blue light B (having a wavelength of 486 nm) is denoted by B. T indicates being related to the meridian plane, and S indicates being related to the sagittal plane. Moreover, in  FIG. 20A  to  FIG. 20L , the maximum scale of the longitudinal axis is ±50.000 μm. 
     As shown in  FIG. 17 , the wide-angle lens  1000  includes, sequentially arranged from the object side (L 1  side), the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , the diaphragm  180 , the fifth lens  150 , the sixth lens  160  and the seventh lens  170 . Among them, the sixth lens  160  and the seventh lens  170  are bonded together by an adhesive to constitute a cemented lens. 
     Here, the wide-angle lens  1000  in this embodiment has the same basic structure (that is, whether each of the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , the fifth lens  150 , the sixth lens  160  and the seventh lens  170  has positive refractive power or negative refractive power, whether each of these lenses is a glass lens or plastic lens, whether the object side surface and the image side surface of each of these lenses are convex surfaces or concave surfaces, and whether the object side surface and the image side surface are spherical surfaces or aspheric surfaces) as that of the wide-angle lens of Embodiment 1, and thus the details thereof will be omitted. 
     In addition, as shown in  FIG. 17 , similarly to Embodiment 1, the light-shielding sheet  190  is provided between the second lens  120  and the third lens  130 , the filter  200  is arranged on the image side of the seventh lens  170 , and the imaging element  300  is arranged on the image side of the filter  200 . 
     In this embodiment, in the lens system as a whole, the effective focal length f is 1.021 mm, the object-to-image distance (total track) d is 13.398 mm, the F value (image space F/#) is 2, the maximum HFOV (maximum half field angle) is 108 degrees, and the entrance pupil diameter HEP is 0.511 mm. 
     Table 9 shows physical properties of each surface of the wide-angle lens  1000  of this embodiment. Table 10-1 and Table 10-2 show aspheric coefficients of each surface of the wide-angle lens  1000  of this embodiment. 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                 TABLE 9 
               
               
                   
               
               
                   
                   
                   
                   
                   
                 Effective 
                 Effective 
                 Effective 
               
               
                   
                 Radius of 
                   
                   
                   
                 focal 
                 focal 
                 focal 
               
               
                 Surface 
                 curvature 
                 Thickness 
                 N d   
                 v d   
                 length 
                 length 
                 length 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 1  
                 11.850 
                 1.800 
                 1.871 
                 40.73 
                 −4.662 
                 −1.258 
                 4.142 
               
               
                 2  
                 2.810 
                 1.790 
               
               
                 3* 
                 21.109 
                 0.610 
                 1.544 
                 56.4 
                 −2.419 
               
               
                 4* 
                 1.226 
                 1.511 
               
               
                 5* 
                 −41.052 
                 0.645 
                 1.544 
                 56.4 
                 7.227 
                 3.259 
               
               
                 6* 
                 −3.608 
                 0.559 
               
               
                 7* 
                 35.384 
                 0.625 
                 1.635 
                 23.9 
                 5.224 
               
               
                 8* 
                 −3.636 
                 0.050 
               
               
                 9  
                 Infinite 
                 0.157 
               
               
                 (diaphragm) 
               
               
                 10  
                 6.330 
                 1.200 
                 1.697 
                 55.46 
                 3.312 
                   
                 3.679 
               
               
                 11  
                 −3.350 
                 0.180 
               
               
                 12*  
                 −5.730 
                 0.510 
                 1.635 
                 23.9 
                 −1.201 
                 9.670 
               
               
                 13*  
                 0.910 
                 2.250 
                 1.544 
                 56.4 
                 1.592 
               
               
                 14*  
                 −2.306 
                 0.986 
               
               
                 15  
                 Infinite 
                 0.400 
               
               
                 16  
                 Infinite 
                 0.125 
               
               
                   
               
            
           
         
       
     
     In Table 9 above, the radius of curvature, thickness, and effective focal length are in units of mm. N d  represents a refractive index for a ray of 587.56 nm. v d  represents the Abbe number. * represents an aspheric surface. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 10-1 
               
               
                   
               
               
                 Surface 
                 c (1/radius of curvature) 
                 K 
                 A4 
                 A6 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 3 
                  4.73738E−02 
                 0.00000E+00 
                 −5.16461E−03  
                 2.97096E−03 
               
               
                 4 
                  8.15727E−01 
                 −3.85594E+00  
                 2.02517E−01 
                 −7.83664E−02  
               
               
                 5 
                 −2.43593E−02 
                 0.00000E+00 
                 7.18080E−04 
                 1.54312E−02 
               
               
                 6 
                 −2.77185E−01 
                 0.00000E+00 
                 1.27000E−02 
                 1.84355E−02 
               
               
                 7 
                  2.82614E−02 
                 0.00000E+00 
                 1.29430E−02 
                 2.83444E−02 
               
               
                 8 
                 −2.75058E−01 
                 0.00000E+00 
                 5.20665E−03 
                 2.87756E−02 
               
               
                 12 
                 −1.74511E−01 
                 0.00000E+00 
                 −2.22912E−02  
                 −2.24026E−04  
               
               
                 13 
                  1.09890E+00 
                 −1.00000E+00  
                 5.45916E−02 
                 −8.55229E−02  
               
               
                 14 
                 −4.33708E−01 
                 0.00000E+00 
                 5.56964E−02 
                 −4.87201E−02  
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 10-2 
               
               
                   
               
               
                 Surface 
                 A8 
                 A10 
                 A12 
                 A14 
                 A16 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 3 
                 −1.12779E−03  
                  1.69605E−04 
                 −9.24708E−06  
                 0.00000E+00 
                 0.00000E+00 
               
               
                 4 
                 5.54759E−02 
                 −1.43828E−02 
                 −3.40212E−05  
                 0.00000E+00 
                 0.00000E+00 
               
               
                 5 
                 4.27755E−03 
                 −5.97392E−03 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 6 
                 1.27283E−03 
                 −1.01399E−02 
                 2.46941E−03 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 7 
                 −2.19533E−02  
                  8.91100E−03 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 8 
                 −2.59952E−02  
                  1.31396E−02 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 12 
                 −5.53989E−03  
                  2.10400E−02 
                 −2.03506E−02  
                 6.17103E−03 
                 0.00000E+00 
               
               
                 13 
                 7.91865E−02 
                 −3.44941E−02 
                 3.84031E−03 
                 7.90842E−04 
                 0.00000E+00 
               
               
                 14 
                 4.18221E−02 
                 −1.79457E−02 
                 3.88481E−03 
                 −3.05248E−04  
                 0.00000E+00 
               
               
                   
               
            
           
         
       
     
     In Table 10-1 and Table 10-2 above, in a case where a lens surface is a convex surface protruding toward the object side or a concave surface recessed toward the object side, its radius of curvature is set to a positive value; in a case where a lens surface is a convex surface protruding toward the image side or a concave surface recessed toward the image side, its radius of curvature is set to a negative value. 
     In addition, Table 10-1 and Table 10-2 above show the aspheric coefficients A4, A6, A8, A10, A12, A14 and A16 of each of the aspheric surfaces, which satisfy Expression 1 above. 
     Here, in the wide-angle lens  1000 , the object-to-image distance d is 13.398 mm, and the entrance pupil diameter HEP is 0.511 mm. Therefore, the following condition 1 is satisfied: 
         d/HEP&lt; 29.000  (1)
 
     In condition 1, if d/HEP is 29.000 or greater, it is difficult to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     In contrast, in this embodiment, since condition 1 is satisfied, it is easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     Particularly, in this embodiment, since d/HEP&lt;27.000 is satisfied, it is relatively easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     In addition, in the wide-angle lens  1000 , the object-to-image distance d is 13.398 mm, and the effective focal length f of the lens system as a whole is 1.021 mm. Therefore, the following condition 2 is satisfied: 
       11.000 &lt;d/f&lt; 15.000  (2)
 
     In condition 2, if d/f is 11.000 or less, it is difficult to appropriately correct various aberrations. On the other hand, if d/f is 15.000 or greater, the overall length of the lens system becomes excessively large. 
     In contrast, in this embodiment, since condition 2 is satisfied, it is easy to appropriately correct various aberrations, making it easy to achieve good optical characteristics. Moreover, it is possible to prevent the lens system from becoming excessively large while avoiding an excessively large overall length of the lens system. 
     In addition, in the wide-angle lens  1000 , the effective focal length f of the lens system as a whole is 1.021 mm, and the entrance pupil diameter HEP is 0.511 mm. Therefore, the following condition 3 is satisfied: 
         f/HEP&lt; 2.3  (3)
 
     In condition 3, if f/HEP is 2.3 or greater, it is difficult to ensure the brightness. 
     In contrast, in this embodiment, since condition 3 is satisfied, it is possible to ensure the brightness and to enable application in a high-density imaging element. 
     In addition, in the wide-angle lens  1000 , the combined effective focal length f1234 of the first lens  110 , the second lens  120 , the third lens  130 , and the fourth lens  140  is 4.142 mm, and the combined effective focal length f567 of the fifth lens  150 , the sixth lens  160 , and the seventh lens  170  is 3.679 mm. Therefore, the following condition 4 is satisfied: 
       0.800 &lt;f 1234 /f 4567&lt;8.000  (4)
 
     In condition 4, if f1234/f567 is 0.800 or less, the refractive power of the front lens group composed of the first lens, the second lens, the third lens, and the fourth lens is excessively high, making it difficult to appropriately correct various aberrations. On the other hand, if f1234/f567 is 8.000 or greater, the refractive power of the front lens group composed of the first lens, the second lens, the third lens, and the fourth lens is excessively low, making it difficult to reduce the diameter of each lens of the front lens group and to miniaturize the wide-angle lens as a whole. 
     In contrast, in this embodiment, since condition 4 is satisfied, it is easy to appropriately correct various aberrations and to realize miniaturization. 
     In addition, in the wide-angle lens  1000 , the combined effective focal length f567 of the fifth lens  150 , the sixth lens  160 , and the seventh lens  170  is 3.679 mm, and the effective focal length f of the lens system as a whole is 1.021 mm. Therefore, the following condition 5 is satisfied: 
       2.800 &lt;f 567 /f&lt; 3.850  (5)
 
     In condition 5, if f567/f is 2.800 or less, the refractive power of the rear lens group composed of the fifth lens, the sixth lens, and the seventh lens is excessively high, making it difficult to appropriately correct various aberrations, especially chromatic aberration. On the other hand, if f567/f is 3.850 or greater, it is difficult to reduce the diameter of each lens and the object-to-image distance, thus making it difficult to miniaturize the wide-angle lens as a whole. 
     In contrast, in this embodiment, since condition 5 is satisfied, it is easy to appropriately correct various aberrations, especially chromatic aberration, and to realize miniaturization. 
     In summary, in this embodiment, by configuring the wide-angle lens  1000  as above, as shown in  FIG. 18A  to  FIG. 20L , it is easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
       FIG. 21  illustrates a wide-angle lens according to Embodiment 6 of the disclosure.  FIG. 22A  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 6 of the disclosure.  FIG. 22B  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 6 of the disclosure.  FIG. 23A  illustrates lateral chromatic aberration (transverse chromatic aberration) of the wide-angle lens according to Embodiment 6 of the disclosure.  FIG. 23B  illustrates spherical aberration (longitudinal aberration) of the wide-angle lens according to Embodiment 6 of the disclosure.  FIG. 24A  to  FIG. 24L  illustrate transverse aberration of the wide-angle lens according to Embodiment 6 of the disclosure. Here, in  FIG. 22A ,  FIG. 22B ,  FIG. 23A ,  FIG. 23B , and  FIG. 24A  to  FIG. 24L , a correlation curve of red light R (having a wavelength of 656 nm) is denoted by R, a correlation curve of green light G (having a wavelength of 588 nm) is denoted by G, and a correlation curve of blue light B (having a wavelength of 486 nm) is denoted by B. T indicates being related to the meridian plane, and S indicates being related to the sagittal plane. Moreover, in  FIG. 24A  to  FIG. 24L , the maximum scale of the longitudinal axis is ±50.000 μm. 
     As shown in  FIG. 21 , the wide-angle lens  1000  includes, sequentially arranged from the object side (L 1  side), the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , the diaphragm  180 , the fifth lens  150 , the sixth lens  160  and the seventh lens  170 . Among them, the sixth lens  160  and the seventh lens  170  are bonded together by an adhesive to constitute a cemented lens. 
     Here, the wide-angle lens  1000  in this embodiment has the same basic structure (that is, whether each of the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , the fifth lens  150 , the sixth lens  160  and the seventh lens  170  has positive refractive power or negative refractive power, whether each of these lenses is a glass lens or plastic lens, whether the object side surface and the image side surface of each of these lenses are convex surfaces or concave surfaces, and whether the object side surface and the image side surface are spherical surfaces or aspheric surfaces) as that of the wide-angle lens of Embodiment 1, and thus the details thereof will be omitted. 
     In addition, as shown in  FIG. 21 , similarly to Embodiment 1, the light-shielding sheet  190  is provided between the second lens  120  and the third lens  130 , the filter  200  is arranged on the image side of the seventh lens  170 , and the imaging element  300  is arranged on the image side of the filter  200 . 
     In this embodiment, in the lens system as a whole, the effective focal length f is 1.018 mm, the object-to-image distance (total track) d is 13.383 mm, the F value (image space F/#) is 2, the maximum HFOV (maximum half field angle) is 108 degrees, and the entrance pupil diameter HEP is 0.509 mm. 
     Table 11 shows physical properties of each surface of the wide-angle lens  1000  of this embodiment. Table 12-1 and Table 12-2 show aspheric coefficients of each surface of the wide-angle lens  1000  of this embodiment. 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                 TABLE 11 
               
               
                   
               
               
                   
                   
                   
                   
                   
                 Effective 
                 Effective 
                 Effective 
               
               
                   
                 Radius of 
                   
                   
                   
                 focal 
                 focal 
                 focal 
               
               
                 Surface 
                 curvature 
                 Thickness 
                 N d   
                 v d   
                 length 
                 length 
                 length 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 1  
                 12.500 
                 1.700 
                 1.871 
                 40.73 
                 −4.748 
                 −1.310 
                 4.528 
               
               
                 2  
                 2.910 
                 1.880 
                 1.000 
               
               
                 3* 
                 9.149 
                 0.600 
                 1.544 
                 56.4 
                 −2.585 
               
               
                 4* 
                 1.191 
                 1.354 
                 1.000 
               
               
                 5* 
                 −14.140 
                 0.750 
                 1.544 
                 56.4 
                 9.374 
                 3.338 
               
               
                 6* 
                 −3.818 
                 0.381 
                 1.000 
               
               
                 7* 
                 −22.250 
                 0.722 
                 1.635 
                 23.9 
                 4.796 
               
               
                 8* 
                 −2.713 
                 0.050 
                 1.000 
               
               
                 9  
                 Infinite 
                 0.130 
                 1.000 
               
               
                 (diaphragm) 
               
               
                 10  
                 7.740 
                 1.320 
                 1.697 
                 55.46 
                 2.821 
                   
                 3.546 
               
               
                 11  
                 −2.450 
                 0.199 
                 1.000 
               
               
                 12*  
                 −3.600 
                 0.510 
                 1.635 
                 23.9 
                 −1.147 
                 10.463 
               
               
                 13*  
                 0.963 
                 2.282 
                 1.544 
                 56.4 
                 1.648 
               
               
                 14*  
                 −2.141 
                 0.980 
                 1.000 
               
               
                 15  
                 Infinite 
                 0.400 
               
               
                 16  
                 Infinite 
                 0.125 
               
               
                   
               
            
           
         
       
     
     In Table 11 above, the radius of curvature, thickness, and effective focal length are in units of mm. N d  represents a refractive index for a ray of 587.56 nm. v d  represents the Abbe number. * represents an aspheric surface. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 12-1 
               
               
                   
               
               
                 Surface 
                 c (1/radius of curvature) 
                 K 
                 A4 
                 A6 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 3 
                  1.09306E−01 
                 0.00000E+00 
                 −4.51092E−03  
                 2.92728E−03 
               
               
                 4 
                  8.39842E−01 
                 −3.71100E+00  
                 2.15910E−01 
                 −7.58275E−02  
               
               
                 5 
                 −7.07214E−02 
                 0.00000E+00 
                 −5.47555E−03  
                 1.09203E−02 
               
               
                 6 
                 −2.61938E−01 
                 0.00000E+00 
                 1.43606E−02 
                 2.26240E−02 
               
               
                 7 
                 −4.49438E−02 
                 0.00000E+00 
                 1.40010E−02 
                 4.01310E−02 
               
               
                 8 
                 −3.68664E−01 
                 0.00000E+00 
                 1.66786E−02 
                 2.21644E−02 
               
               
                 12 
                 −2.77778E−01 
                 0.00000E+00 
                 −2.23667E−02  
                 7.48072E−03 
               
               
                 13 
                  1.03842E+00 
                 −1.00000E+00  
                 4.72309E−02 
                 −6.05266E−02  
               
               
                 14 
                 −4.67071E−01 
                 0.00000E+00 
                 5.78738E−02 
                 −4.73130E−02  
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 12-2 
               
               
                   
               
               
                 Surface 
                 A8 
                 A10 
                 A12 
                 A14 
                 A16 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 3 
                 −1.14938E−03 
                  1.63223E−04 
                 −7.82147E−06  
                 0.00000E+00 
                 0.00000E+00 
               
               
                 4 
                  5.61909E−02 
                 −1.28652E−02 
                 −3.10366E−04  
                 0.00000E+00 
                 0.00000E+00 
               
               
                 5 
                  2.71037E−03 
                 −6.63668E−03 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 6 
                 −3.16016E−03 
                 −9.85165E−03 
                 2.97746E−03 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 7 
                 −1.96461E−02 
                  8.38631E−03 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 8 
                 −1.03312E−02 
                  1.03923E−02 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 12 
                 −8.59213E−03 
                  1.81642E−02 
                 −1.67818E−02  
                 5.17215E−03 
                 0.00000E+00 
               
               
                 13 
                  5.15225E−02 
                 −2.02257E−02 
                 1.88707E−03 
                 3.30690E−04 
                 0.00000E+00 
               
               
                 14 
                  4.12895E−02 
                 −1.76625E−02 
                 3.69776E−03 
                 −2.59955E−04  
                 0.00000E+00 
               
               
                   
               
            
           
         
       
     
     In Table 12-1 and Table 12-2 above, in a case where a lens surface is a convex surface protruding toward the object side or a concave surface recessed toward the object side, its radius of curvature is set to a positive value; in a case where a lens surface is a convex surface protruding toward the image side or a concave surface recessed toward the image side, its radius of curvature is set to a negative value. 
     In addition, Table 12-1 and Table 12-2 above show the aspheric coefficients A4, A6, A8, A10, A12, A14 and A16 of each of the aspheric surfaces, which satisfy Expression 1 above. 
     Here, in the wide-angle lens  1000 , the object-to-image distance d is 13.383 mm, and the entrance pupil diameter HEP is 0.509 mm. Therefore, the following condition 1 is satisfied: 
         d/HEP&lt; 29.000  (1)
 
     In condition 1, if d/HEP is 29.000 or greater, it is difficult to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     In contrast, in this embodiment, since condition 1 is satisfied, it is easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     Particularly, in this embodiment, since d/HEP&lt;27.000 is satisfied, it is relatively easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     In addition, in the wide-angle lens  1000 , the object-to-image distance d is 13.383 mm, and the effective focal length f of the lens system as a whole is 1.018 mm. Therefore, the following condition 2 is satisfied: 
       11.000 &lt;d/f&lt; 15.000  (2)
 
     In condition 2, if d/f is 11.000 or less, it is difficult to appropriately correct various aberrations. On the other hand, if d/f is 15.000 or greater, the overall length of the lens system becomes excessively large. 
     In contrast, in this embodiment, since condition 2 is satisfied, it is easy to appropriately correct various aberrations, making it easy to achieve good optical characteristics. Moreover, it is possible to prevent the lens system from becoming excessively large while avoiding an excessively large overall length of the lens system. 
     In addition, in the wide-angle lens  1000 , the effective focal length f of the lens system as a whole is 1.018 mm, and the entrance pupil diameter HEP is 0.509 mm. Therefore, the following condition 3 is satisfied: 
         f/HEP&lt; 2.3  (3)
 
     In condition 3, if f/HEP is 2.3 or greater, it is difficult to ensure the brightness. 
     In contrast, in this embodiment, since condition 3 is satisfied, it is possible to ensure the brightness and to enable application in a high-density imaging element. 
     In addition, in the wide-angle lens  1000 , the combined effective focal length f1234 of the first lens  110 , the second lens  120 , the third lens  130 , and the fourth lens  140  is 4.528 mm, and the combined effective focal length f567 of the fifth lens  150 , the sixth lens  160 , and the seventh lens  170  is 3.546 mm. Therefore, the following condition 4 is satisfied: 
       0.800 &lt;f 1234 /f 4567&lt;8.000  (4)
 
     In condition 4, if f1234/f567 is 0.800 or less, the refractive power of the front lens group composed of the first lens, the second lens, the third lens, and the fourth lens is excessively high, making it difficult to appropriately correct various aberrations. On the other hand, if f1234/f567 is 8.000 or greater, the refractive power of the front lens group composed of the first lens, the second lens, the third lens, and the fourth lens is excessively low, making it difficult to reduce the diameter of each lens of the front lens group and to miniaturize the wide-angle lens as a whole. 
     In contrast, in this embodiment, since condition 4 is satisfied, it is easy to appropriately correct various aberrations and to realize miniaturization. 
     In addition, in the wide-angle lens  1000 , the combined effective focal length f567 of the fifth lens  150 , the sixth lens  160 , and the seventh lens  170  is 3.546 mm, and the effective focal length f of the lens system as a whole is 1.018 mm. Therefore, the following condition 5 is satisfied: 
       2.800 &lt;f 567 /f&lt; 3.850  (5)
 
     In condition 5, if f567/f is 2.800 or less, the refractive power of the rear lens group composed of the fifth lens, the sixth lens, and the seventh lens is excessively high, making it difficult to appropriately correct various aberrations, especially chromatic aberration. On the other hand, if f567/f is 3.850 or greater, it is difficult to reduce the diameter of each lens and the object-to-image distance, thus making it difficult to miniaturize the wide-angle lens as a whole. 
     In contrast, in this embodiment, since condition 5 is satisfied, it is easy to appropriately correct various aberrations, especially chromatic aberration, and to realize miniaturization. 
     In summary, in this embodiment, by configuring the wide-angle lens  1000  as above, as shown in  FIG. 22A  to  FIG. 24L , it is easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
       FIG. 25  illustrates a wide-angle lens according to Embodiment 7 of the disclosure.  FIG. 26A  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 7 of the disclosure.  FIG. 26B  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 7 of the disclosure.  FIG. 27A  illustrates lateral chromatic aberration (transverse chromatic aberration) of the wide-angle lens according to Embodiment 7 of the disclosure.  FIG. 27B  illustrates spherical aberration (longitudinal aberration) of the wide-angle lens according to Embodiment 7 of the disclosure.  FIG. 28A  to  FIG. 28L  illustrate transverse aberration of the wide-angle lens according to Embodiment 7 of the disclosure. Here, in  FIG. 26A ,  FIG. 26B ,  FIG. 27A ,  FIG. 27B , and  FIG. 28A  to  FIG. 28L , a correlation curve of red light R (having a wavelength of 656 nm) is denoted by R, a correlation curve of green light G (having a wavelength of 588 nm) is denoted by G, and a correlation curve of blue light B (having a wavelength of 486 nm) is denoted by B. T indicates being related to the meridian plane, and S indicates being related to the sagittal plane. Moreover, in  FIG. 28A  to  FIG. 28L , a maximum scale of the longitudinal axis is ±50.000 μm. 
     As shown in  FIG. 25 , the wide-angle lens  1000  includes, sequentially arranged from the object side (L 1  side), the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , the diaphragm  180 , the fifth lens  150 , the sixth lens  160  and the seventh lens  170 . Among them, the sixth lens  160  and the seventh lens  170  are bonded together by an adhesive to constitute a cemented lens. 
     Here, the wide-angle lens  1000  in this embodiment has the same basic structure (that is, whether each of the first lens  110  (located closest to the object side), the second lens  120  (located on the image side of and adjacent to the first lens  110 ), the third lens  130 , the fourth lens  140 , the fifth lens  150 , the sixth lens  160  and the seventh lens  170  has positive refractive power or negative refractive power, whether each of these lenses is a glass lens or plastic lens, whether the object side surface and the image side surface of each of these lenses are convex surfaces or concave surfaces, and whether the object side surface and the image side surface are spherical surfaces or aspheric surfaces) as that of the wide-angle lens of Embodiment 1, and thus the details thereof will be omitted. 
     In addition, as shown in  FIG. 25 , similarly to Embodiment 1, the light-shielding sheet  190  is provided between the second lens  120  and the third lens  130 , the filter  200  is arranged on the image side of the seventh lens  170 , and the imaging element  300  is arranged on the image side of the filter  200 . 
     In this embodiment, in the lens system as a whole, the effective focal length f is 1.019 mm, the object-to-image distance (total track) d is 13.381 mm, the F value (image space F/#) is 2.0163, the maximum HFOV (maximum half field angle) is 108 degrees, and the entrance pupil diameter HEP is 0.505 mm. 
     Table 13 shows physical properties of each surface of the wide-angle lens  1000  of this embodiment. Table 14-1 and Table 14-2 show aspheric coefficients of each surface of the wide-angle lens  1000  of this embodiment. 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                 TABLE 13 
               
               
                   
               
               
                   
                   
                   
                   
                   
                 Effective 
                 Effective 
                 Effective 
               
               
                   
                 Radius of 
                   
                   
                   
                 focal 
                 focal 
                 focal 
               
               
                 Surface 
                 curvature 
                 Thickness 
                 N d   
                 v d   
                 length 
                 length 
                 length 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 1  
                 12.500 
                 1.700 
                 1.871 
                 40.73 
                 −4.748 
                 −1.310 
                 4.815 
               
               
                 2  
                 2.910 
                 1.880 
               
               
                 3* 
                 9.138 
                 0.600 
                 1.544 
                 56.4 
                 −2.586 
               
               
                 4* 
                 1.191 
                 1.354 
               
               
                 5* 
                 −11.789 
                 0.750 
                 1.544 
                 56.4 
                 10.047 
                 3.394 
               
               
                 6* 
                 −3.818 
                 0.381 
               
               
                 7* 
                 −22.250 
                 0.710 
                 1.635 
                 23.9 
                 4.797 
               
               
                 8* 
                 −2.713 
                 0.050 
               
               
                 9  
                 Infinite 
                 0.116 
               
               
                 (diaphragm) 
               
               
                 10  
                 7.740 
                 1.320 
                 1.697 
                 55.46 
                 2.821 
                   
                 3.557 
               
               
                 11  
                 −2.450 
                 0.225 
               
               
                 12*  
                 −3.600 
                 0.510 
                 1.635 
                 23.9 
                 −1.147 
                 10.463 
               
               
                 13*  
                 0.963 
                 2.282 
                 1.544 
                 56.4 
                 1.648 
               
               
                 14*  
                 −2.141 
                 0.978 
               
               
                 15  
                 Infinite 
                 0.400 
               
               
                 16  
                 Infinite 
                 0.125 
               
               
                   
               
            
           
         
       
     
     In Table 11 above, the radius of curvature, thickness, and effective focal length are in units of mm. N d  represents a refractive index for a ray of 587.56 nm. v d  represents the Abbe number. * represents an aspheric surface. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 14-1 
               
               
                   
               
               
                 Surface 
                 c (1/radius of curvature) 
                 K 
                 A4 
                 A6 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 3 
                  1.09439E−01 
                 0.00000E+00 
                 −4.39546E−03  
                 2.94241E−03 
               
               
                 4 
                  8.39842E−01 
                 −3.71100E+00  
                 2.15910E−01 
                 −7.58275E−02  
               
               
                 5 
                 −8.48248E−02 
                 0.00000E+00 
                 −5.99821E−03  
                 9.40179E−03 
               
               
                 6 
                 −2.61938E−01 
                 0.00000E+00 
                 1.43606E−02 
                 2.26240E−02 
               
               
                 7 
                 −4.49438E−02 
                 0.00000E+00 
                 1.40010E−02 
                 4.01310E−02 
               
               
                 8 
                 −3.68664E−01 
                 0.00000E+00 
                 1.66786E−02 
                 2.21644E−02 
               
               
                 12 
                 −2.77778E−01 
                 0.00000E+00 
                 −2.23667E−02  
                 7.48072E−03 
               
               
                 13 
                  1.03842E+00 
                 −1.00000E+00  
                 4.72309E−02 
                 −6.05266E−02  
               
               
                 14 
                 −4.67071E−01 
                 0.00000E+00 
                 5.76337E−02 
                 −4.72421E−02  
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 14-2 
               
               
                   
               
               
                 Surface 
                 A8 
                 A10 
                 A12 
                 A14 
                 A16 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 3 
                 −1.15296E−03 
                  1.63212E−04 
                 −7.75247E−06  
                 0.00000E+00 
                 0.00000E+00 
               
               
                 4 
                  5.61909E−02 
                 −1.28652E−02 
                 −3.10366E−04  
                 0.00000E+00 
                 0.00000E+00 
               
               
                 5 
                  3.12004E−03 
                 −6.74245E−03 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 6 
                 −3.16016E−03 
                 −9.85165E−03 
                 2.97746E−03 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 7 
                 −1.96461E−02 
                  8.38631E−03 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 8 
                 −1.03312E−02 
                  1.03923E−02 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 12 
                 −8.59213E−03 
                  1.81642E−02 
                 −1.67818E−02  
                 5.17215E−03 
                 0.00000E+00 
               
               
                 13 
                  5.15225E−02 
                 −2.02257E−02 
                 1.88707E−03 
                 3.30690E−04 
                 0.00000E+00 
               
               
                 14 
                  4.13120E−02 
                 −1.76585E−02 
                 3.69817E−03 
                 −2.61279E−04  
                 0.00000E+00 
               
               
                   
               
            
           
         
       
     
     In Table 14-1 and Table 14-2 above, in a case where a lens surface is a convex surface protruding toward the object side or a concave surface recessed toward the object side, its radius of curvature is set to a positive value; in a case where a lens surface is a convex surface protruding toward the image side or a concave surface recessed toward the image side, its radius of curvature is set to a negative value. 
     In addition, Table 14-1 and Table 14-2 above show the aspheric coefficients A4, A6, A8, A10, A12, A14 and A16 of each of the aspheric surfaces, which satisfy Expression 1 above. 
     Here, in the wide-angle lens  1000 , the object-to-image distance d is 13.381 mm, and the entrance pupil diameter HEP is 0.505 mm. Therefore, the following condition 1 is satisfied: 
         d/HEP&lt; 29.000  (1)
 
     In condition 1, if d/HEP is 29.000 or greater, it is difficult to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     In contrast, in this embodiment, since condition 1 is satisfied, it is easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     Particularly, in this embodiment, since d/HEP&lt;27.000 is satisfied, it is relatively easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     In addition, in the wide-angle lens  1000 , the object-to-image distance d is 13.381 mm, and the effective focal length f of the lens system as a whole is 1.019 mm. Therefore, the following condition 2 is satisfied: 
       11.000 &lt;d/f&lt; 15.000  (2)
 
     In condition 2, if d/f is 11.000 or less, it is difficult to appropriately correct various aberrations. On the other hand, if d/f is 15.000 or greater, the overall length of the lens system becomes excessively large. 
     In contrast, in this embodiment, since condition 2 is satisfied, it is easy to appropriately correct various aberrations, making it easy to achieve good optical characteristics. Moreover, it is possible to prevent the lens system from becoming excessively large while avoiding an excessively large overall length of the lens system. 
     In addition, in the wide-angle lens  1000 , the effective focal length f of the lens system as a whole is 1.019 mm, and the entrance pupil diameter HEP is 0.505 mm. Therefore, the following condition 3 is satisfied: 
         f/HEP&lt; 2.3  (3)
 
     In condition 3, if f/HEP is 2.3 or greater, it is difficult to ensure the brightness. 
     In contrast, in this embodiment, since condition 3 is satisfied, it is possible to ensure the brightness and to enable application in a high-density imaging element. 
     In addition, in the wide-angle lens  1000 , the combined effective focal length f1234 of the first lens  110 , the second lens  120 , the third lens  130 , and the fourth lens  140  is 4.815 mm, and the combined effective focal length f567 of the fifth lens  150 , the sixth lens  160 , and the seventh lens  170  is 3.557 mm. Therefore, the following condition 4 is satisfied: 
       0.800 &lt;f 1234 /f 4567&lt;8.000  (4)
 
     In condition 4, if f1234/f567 is 0.800 or less, the refractive power of the front lens group composed of the first lens, the second lens, the third lens, and the fourth lens is excessively high, making it difficult to appropriately correct various aberrations. On the other hand, if f1234/f567 is 8.000 or greater, the refractive power of the front lens group composed of the first lens, the second lens, the third lens, and the fourth lens is excessively low, making it difficult to reduce the diameter of each lens of the front lens group and to miniaturize the wide-angle lens as a whole. 
     In contrast, in this embodiment, since condition 4 is satisfied, it is easy to appropriately correct various aberrations and to realize miniaturization. 
     In addition, in the wide-angle lens  1000 , the combined effective focal length f567 of the fifth lens  150 , the sixth lens  160 , and the seventh lens  170  is 3.557 mm, and the effective focal length f of the lens system as a whole is 1.019 mm. Therefore, the following condition 5 is satisfied: 
       2.800&lt; f 567/ f&lt; 3.850  (5)
 
     In condition 5, if f567/f is 2.800 or less, the refractive power of the rear lens group composed of the fifth lens, the sixth lens, and the seventh lens is excessively high, making it difficult to appropriately correct various aberrations, especially chromatic aberration. On the other hand, if f567/f is 3.850 or greater, it is difficult to reduce the diameter of each lens and the object-to-image distance, thus making it difficult to miniaturize the wide-angle lens as a whole. 
     In contrast, in this embodiment, since condition 5 is satisfied, it is easy to appropriately correct various aberrations, especially chromatic aberration, and to realize miniaturization. 
     In summary, in this embodiment, by configuring the wide-angle lens  1000  as above, as shown in  FIG. 26A  to  FIG. 28L , it is easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
       FIG. 29  illustrates a wide-angle lens according to Embodiment 8 of the disclosure.  FIG. 30A  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 8 of the disclosure.  FIG. 30B  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 8 of the disclosure.  FIG. 31A  illustrates lateral chromatic aberration (transverse chromatic aberration) of the wide-angle lens according to Embodiment 8 of the disclosure.  FIG. 31B  illustrates spherical aberration (longitudinal aberration) of the wide-angle lens according to Embodiment 8 of the disclosure.  FIG. 32A  to  FIG. 32L  illustrate transverse aberration of the wide-angle lens according to Embodiment 8 of the disclosure. Here, in  FIG. 30A ,  FIG. 30B ,  FIG. 31A ,  FIG. 31B , and  FIG. 32A  to  FIG. 32L , a correlation curve of red light R (having a wavelength of 656 nm) is denoted by R, a correlation curve of green light G (having a wavelength of 588 nm) is denoted by G, and a correlation curve of blue light B (having a wavelength of 486 nm) is denoted by B. T indicates being related to the meridian plane, and S indicates being related to the sagittal plane. Moreover, in  FIG. 32A  to  FIG. 32L , the maximum scale of the longitudinal axis is ±50.000 μm. 
     As shown in  FIG. 29 , the wide-angle lens  1000  includes, sequentially arranged from the object side (L 1  side), the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , the diaphragm  180 , the fifth lens  150 , the sixth lens  160  and the seventh lens  170 . Among them, the sixth lens  160  and the seventh lens  170  are bonded together by an adhesive to constitute a cemented lens. 
     Here, the wide-angle lens  1000  in this embodiment has the same basic structure (that is, whether each of the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , the fifth lens  150 , the sixth lens  160  and the seventh lens  170  has positive refractive power or negative refractive power, whether each of these lenses is a glass lens or plastic lens, whether the object side surface and the image side surface of each of these lenses are convex surfaces or concave surfaces, and whether the object side surface and the image side surface are spherical surfaces or aspheric surfaces) as that of the wide-angle lens of Embodiment 1, and thus the details thereof will be omitted. 
     In addition, as shown in  FIG. 29 , similarly to Embodiment 1, the light-shielding sheet  190  is provided between the second lens  120  and the third lens  130 , the filter  200  is arranged on the image side of the seventh lens  170 , and the imaging element  300  is arranged on the image side of the filter  200 . 
     In this embodiment, in the lens system as a whole, the effective focal length f is 1.030 mm, the object-to-image distance (total track) d is 13.609 mm, the F value (image space F/#) is 2, the maximum HFOV (maximum half field angle) is 106 degrees, and the entrance pupil diameter HEP is 0.515 mm. 
     Table 15 shows physical properties of each surface of the wide-angle lens  1000  of this embodiment. Table 16-1 and Table 16-2 show aspheric coefficients of each surface of the wide-angle lens  1000  of this embodiment. 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                 TABLE 15 
               
               
                   
               
               
                   
                   
                   
                   
                   
                 Effective 
                 Effective 
                 Effective 
               
               
                   
                 Radius of 
                   
                   
                   
                 focal 
                 focal 
                 focal 
               
               
                 Surface 
                 curvature 
                 Thickness 
                 N d   
                 v d   
                 length 
                 length 
                 length 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 1  
                 12.641 
                 1.659 
                 1.804 
                 46.5 
                 −5.702 
                 −1.262 
                 21.864 
               
               
                 2  
                 3.168 
                 1.968 
               
               
                 3* 
                 −22.811 
                 0.600 
                 1.544 
                 56.4 
                 −2.189 
               
               
                 4* 
                 1.268 
                 1.587 
               
               
                 5* 
                 3.542 
                 1.200 
                 1.544 
                 56.4 
                 10.255 
                 3.623 
               
               
                 6* 
                 8.543 
                 0.036 
               
               
                 7* 
                 4.456 
                 0.592 
                 1.639 
                 23.5 
                 4.851 
               
               
                 8* 
                 −9.668 
                 0.248 
               
               
                 9  
                 Infinite 
                 0.078 
               
               
                 (diaphragm) 
               
               
                 10  
                 6.001 
                 1.129 
                 1.697 
                 55.46 
                 2.908 
                   
                 3.125 
               
               
                 11  
                 −2.824 
                 0.247 
               
               
                 12*  
                 −5.445 
                 0.500 
                 1.639 
                 23.5 
                 −1.380 
                 6.310 
               
               
                 13*  
                 1.090 
                 2.170 
                 1.544 
                 56.4 
                 1.720 
               
               
                 14*  
                 −1.971 
                 1.070 
               
               
                 15  
                 Infinite 
                 0.400 
               
               
                 16  
                 Infinite 
                 0.125 
               
               
                   
               
            
           
         
       
     
     In Table 15 above, the radius of curvature, thickness, and effective focal length are in units of mm. N d  represents a refractive index for a ray of 587.56 nm. v d  represents the Abbe number. * represents an aspheric surface. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 16-1 
               
               
                   
               
               
                 Surface 
                 c (1/radius of curvature) 
                 K 
                 A4 
                 A6 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 3 
                 −4.38390E−02  
                 0.00000E+00 
                 1.02948E−02 
                 −1.01140E−03  
               
               
                 4 
                 7.88668E−01 
                 −1.13571E+00  
                 5.66499E−02 
                 1.84231E−03 
               
               
                 5 
                 2.82343E−01 
                 0.00000E+00 
                 −2.18543E−02  
                 5.16357E−03 
               
               
                 6 
                 1.17050E−01 
                 0.00000E+00 
                 −6.48711E−02  
                 −8.41810E−03  
               
               
                 7 
                 2.24418E−01 
                 0.00000E+00 
                 3.04785E−02 
                 1.99197E−02 
               
               
                 8 
                 −1.03429E−01  
                 0.00000E+00 
                 9.05286E−02 
                 3.48783E−02 
               
               
                 12 
                 −1.83670E−01  
                 0.00000E+00 
                 −3.32106E−02  
                 4.95833E−02 
               
               
                 13 
                 9.17180E−01 
                 −3.67711E+00  
                 1.58393E−01 
                 −3.03404E−02  
               
               
                 14 
                 −5.07238E−01  
                 −6.42125E−01  
                 3.25791E−02 
                 −8.99922E−03  
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 16-2 
               
               
                   
               
               
                 Surface 
                 A8 
                 A10 
                 A12 
                 A14 
                 A16 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 3 
                 2.82136E−05 
                 8.57444E−16 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 4 
                 3.99185E−02 
                 −2.56858E−02  
                 9.68214E−03 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 5 
                 −3.88312E−04  
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 6 
                 3.26148E−03 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 7 
                 −6.50576E−03  
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 8 
                 4.33217E−03 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 12 
                 −4.63097E−02  
                 2.53604E−02 
                 −5.68334E−03  
                 0.00000E+00 
                 0.00000E+00 
               
               
                 13 
                 −2.77646E−02  
                 2.45247E−02 
                 −5.43979E−03  
                 0.00000E+00 
                 0.00000E+00 
               
               
                 14 
                 4.06471E−03 
                 −7.04269E−04  
                 4.21913E−05 
                 0.00000E+00 
                 0.00000E+00 
               
               
                   
               
            
           
         
       
     
     In Table 16-1 and Table 16-2 above, in a case where a lens surface is a convex surface protruding toward the object side or a concave surface recessed toward the object side, its radius of curvature is set to a positive value; in a case where a lens surface is a convex surface protruding toward the image side or a concave surface recessed toward the image side, its radius of curvature is set to a negative value. 
     In addition, Table 16-1 and Table 16-2 above show the aspheric coefficients A4, A6, A8, A10, A12, A14 and A16 of each of the aspheric surfaces, which satisfy Expression 1 above. 
     Here, in the wide-angle lens  1000 , the object-to-image distance d is 13.609 mm, and the entrance pupil diameter HEP is 0.515 mm. Therefore, the following condition 1 is satisfied: 
         d/HEP&lt; 29.000  (1)
 
     In condition 1, if d/HEP is 29.000 or greater, it is difficult to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     In contrast, in this embodiment, since condition 1 is satisfied, it is easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     Particularly, in this embodiment, since d/HEP&lt;27.000 is satisfied, it is relatively easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     In addition, in the wide-angle lens  1000 , the object-to-image distance d is 13.609 mm, and the effective focal length f of the lens system as a whole is 1.030 mm. Therefore, the following condition 2 is satisfied: 
       11.000 &lt;d/f&lt; 15.000  (2)
 
     In condition 2, if d/f is 11.000 or less, it is difficult to appropriately correct various aberrations. On the other hand, if d/f is 15.000 or greater, the overall length of the lens system becomes excessively large. 
     In contrast, in this embodiment, since condition 2 is satisfied, it is easy to appropriately correct various aberrations, making it easy to achieve good optical characteristics. Moreover, it is possible to prevent the lens system from becoming excessively large while avoiding an excessively large overall length of the lens system. 
     In addition, in the wide-angle lens  1000 , the effective focal length f of the lens system as a whole is 1.030 mm, and the entrance pupil diameter HEP is 0.515 mm. Therefore, the following condition 3 is satisfied: 
         f/HEP&lt; 2.3  (3)
 
     In condition 3, if f/HEP is 2.3 or greater, it is difficult to ensure the brightness. 
     In contrast, in this embodiment, since condition 3 is satisfied, it is possible to ensure the brightness and to enable application in a high-density imaging element. 
     In addition, in the wide-angle lens  1000 , the combined effective focal length f1234 of the first lens  110 , the second lens  120 , the third lens  130 , and the fourth lens  140  is 21.864 mm, and the combined effective focal length f567 of the fifth lens  150 , the sixth lens  160 , and the seventh lens  170  is 3.125 mm. Therefore, the following condition 4 is satisfied: 
       0.800 &lt;f 1234 /f 4567&lt;8.000  (4)
 
     In condition 4, if f1234/f567 is 0.800 or less, the refractive power of the front lens group composed of the first lens, the second lens, the third lens, and the fourth lens is excessively high, making it difficult to appropriately correct various aberrations. On the other hand, if f1234/f567 is 8.000 or greater, the refractive power of the front lens group composed of the first lens, the second lens, the third lens, and the fourth lens is excessively low, making it difficult to reduce the diameter of each lens of the front lens group and to miniaturize the wide-angle lens as a whole. 
     In contrast, in this embodiment, since condition 4 is satisfied, it is easy to appropriately correct various aberrations and to realize miniaturization. 
     In addition, in the wide-angle lens  1000 , the combined effective focal length f567 of the fifth lens  150 , the sixth lens  160 , and the seventh lens  170  is 3.125 mm, and the effective focal length f of the lens system as a whole is 1.030 mm. Therefore, the following condition 5 is satisfied: 
       2.800&lt; f 567/ f&lt; 3.850  (5)
 
     In condition 5, if f567/f is 2.800 or less, the refractive power of the rear lens group composed of the fifth lens, the sixth lens, and the seventh lens is excessively high, making it difficult to appropriately correct various aberrations, especially chromatic aberration. On the other hand, if f567/f is 3.850 or greater, it is difficult to reduce the diameter of each lens and the object-to-image distance, thus making it difficult to miniaturize the wide-angle lens as a whole. 
     In contrast, in this embodiment, since condition 5 is satisfied, it is easy to appropriately correct various aberrations, especially chromatic aberration, and to realize miniaturization. 
     In summary, in this embodiment, by configuring the wide-angle lens  1000  as above, as shown in  FIG. 30A  to  FIG. 32L , it is easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
       FIG. 33  illustrates a wide-angle lens according to Embodiment 9 of the disclosure.  FIG. 34A  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 9 of the disclosure.  FIG. 34B  illustrates curvature of field and distortion of the wide-angle lens according to Embodiment 9 of the disclosure.  FIG. 35A  illustrates lateral chromatic aberration (transverse chromatic aberration) of the wide-angle lens according to Embodiment 9 of the disclosure.  FIG. 35B  illustrates spherical aberration (longitudinal aberration) of the wide-angle lens according to Embodiment 9 of the disclosure.  FIG. 36A  to  FIG. 36L  illustrate transverse aberration of the wide-angle lens according to Embodiment 9 of the disclosure. Here, in  FIG. 34A ,  FIG. 34B ,  FIG. 35A ,  FIG. 35B , and  FIG. 36A  to  FIG. 36L , a correlation curve of red light R (having a wavelength of 656 nm) is denoted by R, a correlation curve of green light G (having a wavelength of 588 nm) is denoted by G, and a correlation curve of blue light B (having a wavelength of 486 nm) is denoted by B. T indicates being related to the meridian plane, and S indicates being related to the sagittal plane. Moreover, in  FIG. 36A  to  FIG. 36L , a maximum scale of the longitudinal axis is ±50.000 μm. 
     As shown in  FIG. 33 , the wide-angle lens  1000  includes, sequentially arranged from the object side (L 1  side), the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , the diaphragm  180 , the fifth lens  150 , the sixth lens  160  and the seventh lens  170 . Among them, the sixth lens  160  and the seventh lens  170  are bonded together by an adhesive to constitute a cemented lens. 
     Here, the wide-angle lens  1000  in this embodiment has the same basic structure (that is, whether each of the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , the fifth lens  150 , the sixth lens  160  and the seventh lens  170  has positive refractive power or negative refractive power, whether each of these lenses is a glass lens or plastic lens, whether the object side surface and the image side surface of each of these lenses are convex surfaces or concave surfaces, and whether the object side surface and the image side surface are spherical surfaces or aspheric surfaces) as that of the wide-angle lens of Embodiment 1, and thus the details thereof will be omitted. 
     In addition, as shown in  FIG. 33 , similarly to Embodiment 1, the light-shielding sheet  190  is provided between the second lens  120  and the third lens  130 , the filter  200  is arranged on the image side of the seventh lens  170 , and the imaging element  300  is arranged on the image side of the filter  200 . 
     In this embodiment, in the lens system as a whole, the effective focal length f is 1.019 mm, the object-to-image distance (total track) d is 13.397 mm, the F value (image space F/#) is 2.012, the maximum HFOV (maximum half field angle) is 108.004 degrees, and the entrance pupil diameter HEP is 0.506 mm. 
     Table 17 shows physical properties of each surface of the wide-angle lens  1000  of this embodiment. Table 18-1 and Table 18-2 show aspheric coefficients of each surface of the wide-angle lens  1000  of this embodiment. 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                 TABLE 17 
               
               
                   
               
               
                   
                   
                   
                   
                   
                 Effective 
                 Effective 
                 Effective 
               
               
                   
                 Radius of 
                   
                   
                   
                 focal 
                 focal 
                 focal 
               
               
                 Surface 
                 curvature 
                 Thickness 
                 N d   
                 v d   
                 length 
                 length 
                 length 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 1  
                 12.100 
                 1.730 
                 1.871 
                 40.73 
                 −4.823 
                 −1.415 
                 26.363 
               
               
                 2  
                 2.910 
                 1.765 
               
               
                 3* 
                 7.693 
                 0.600 
                 1.544 
                 56.4 
                 −2.800 
               
               
                 4* 
                 1.237 
                 1.517 
               
               
                 5* 
                 −6.607 
                 0.850 
                 1.544 
                 56.4 
                 12.527 
                 4.381 
               
               
                 6* 
                 −3.507 
                 0.202 
               
               
                 7* 
                 −12.641 
                 0.700 
                 1.635 
                 23.9 
                 6.634 
               
               
                 8* 
                 −3.228 
                 0.050 
               
               
                 9  
                 Infinite 
                 0.129 
               
               
                 (diaphragm) 
               
               
                 10  
                 5.000 
                 1.360 
                 1.697 
                 55.46 
                 2.636 
                   
                 3.374 
               
               
                 11  
                 −2.580 
                 0.260 
               
               
                 12*  
                 −3.864 
                 0.550 
                 1.635 
                 23.9 
                 −1.179 
                 10.147 
               
               
                 13*  
                 0.980 
                 2.190 
                 1.544 
                 56.4 
                 1.642 
               
               
                 14*  
                 −2.151 
                 0.969 
               
               
                 15  
                 Infinite 
                 0.400 
               
               
                 16  
                 Infinite 
                 0.125 
               
               
                   
               
            
           
         
       
     
     In Table 17 above, the radius of curvature, thickness, and effective focal length are in units of mm. N d  represents a refractive index for a ray of 587.56 nm. v d  represents the Abbe number. * represents an aspheric surface. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 18-1 
               
               
                   
               
               
                 Surface 
                 c (1/radius of curvature) 
                 K 
                 A4 
                 A6 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 3 
                  1.29990E−01 
                 0.00000E+00 
                 1.79733E−03 
                 −1.14149E−03 
               
               
                 4 
                  8.08669E−01 
                 −4.00000E+00  
                 2.15100E−01 
                 −8.02378E−02 
               
               
                 5 
                 −1.51355E−01 
                 0.00000E+00 
                 −1.09624E−02  
                 −8.73052E−03 
               
               
                 6 
                 −2.85185E−01 
                 0.00000E+00 
                 4.64269E−03 
                  4.90763E−03 
               
               
                 7 
                 −7.91052E−02 
                 0.00000E+00 
                 1.02155E−02 
                  7.50888E−03 
               
               
                 8 
                 −3.09828E−01 
                 0.00000E+00 
                 7.49234E−03 
                  1.54584E−03 
               
               
                 12 
                 −2.58792E−01 
                 0.00000E+00 
                 −3.14257E−02  
                  2.35226E−03 
               
               
                 13 
                  1.02041E+00 
                 −1.00000E+00  
                 3.07479E−02 
                 −4.89661E−02 
               
               
                 14 
                 −4.64857E−01 
                 0.00000E+00 
                 4.79842E−02 
                 −2.97957E−02 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 18-2 
               
               
                   
               
               
                 Surface 
                 A8 
                 A10 
                 A12 
                 A14 
                 A16 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 3 
                 −6.11588E−05  
                  1.50045E−05 
                 3.90615E−08 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 4 
                 4.96308E−02 
                 −1.37651E−02 
                 1.87863E−04 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 5 
                 2.50539E−03 
                 −1.94316E−04 
                 −2.18386E−04  
                 0.00000E+00 
                 0.00000E+00 
               
               
                 6 
                 2.37631E−03 
                  4.68175E−04 
                 1.19525E−03 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 7 
                 1.14133E−02 
                  6.53638E−04 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 8 
                 1.36753E−02 
                 −1.98505E−03 
                 0.00000E+00 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 12 
                 3.38366E−03 
                 −2.00010E−03 
                 6.86525E−04 
                 0.00000E+00 
                 0.00000E+00 
               
               
                 13 
                 2.79270E−02 
                 −5.22149E−03 
                 −1.20343E−04  
                 0.00000E+00 
                 0.00000E+00 
               
               
                 14 
                 2.26165E−02 
                 −7.19858E−03 
                 9.87041E−04 
                 0.00000E+00 
                 0.00000E+00 
               
               
                   
               
            
           
         
       
     
     In Table 18-1 and Table 18-2 above, in a case where a lens surface is a convex surface protruding toward the object side or a concave surface recessed toward the object side, its radius of curvature is set to a positive value; in a case where a lens surface is a convex surface protruding toward the image side or a concave surface recessed toward the image side, its radius of curvature is set to a negative value. 
     In addition, Table 18-1 and Table 18-2 above show the aspheric coefficients A4, A6, A8, A10, A12, A14 and A16 of each of the aspheric surfaces, which satisfy Expression 1 above. 
     Here, in the wide-angle lens  1000 , the object-to-image distance d is 13.397 mm, and the entrance pupil diameter HEP is 0.506 mm. Therefore, the following condition 1 is satisfied: 
         d/HEP&lt; 29.000  (1)
 
     In condition 1, if d/HEP is 29.000 or greater, it is difficult to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     In contrast, in this embodiment, since condition 1 is satisfied, it is easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     Particularly, in this embodiment, since d/HEP&lt;27.000 is satisfied, it is relatively easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     In addition, in the wide-angle lens  1000 , the object-to-image distance d is 13.397 mm, and the effective focal length f of the lens system as a whole is 1.019 mm. Therefore, the following condition 2 is satisfied: 
       11.000 &lt;d/f&lt; 15.000  (2)
 
     In condition 2, if d/f is 11.000 or less, it is difficult to appropriately correct various aberrations. On the other hand, if d/f is 15.000 or greater, the overall length of the lens system becomes excessively large. 
     In contrast, in this embodiment, since condition 2 is satisfied, it is easy to appropriately correct various aberrations, making it easy to achieve good optical characteristics. Moreover, it is possible to prevent the lens system from becoming excessively large while avoiding an excessively large overall length of the lens system. 
     In addition, in the wide-angle lens  1000 , the effective focal length f of the lens system as a whole is 1.019 mm, and the entrance pupil diameter HEP is 0.506 mm. Therefore, the following condition 3 is satisfied: 
         f/HEP&lt; 2.3  (3)
 
     In condition 3, if f/HEP is 2.3 or greater, it is difficult to ensure the brightness. 
     In contrast, in this embodiment, since condition 3 is satisfied, it is possible to ensure the brightness and to enable application in a high-density imaging element. 
     In addition, in the wide-angle lens  1000 , the combined effective focal length f1234 of the first lens  110 , the second lens  120 , the third lens  130 , and the fourth lens  140  is 26.363 mm, and the combined effective focal length f567 of the fifth lens  150 , the sixth lens  160 , and the seventh lens  170  is 3.374 mm. Therefore, the following condition 4 is satisfied: 
       0.800 &lt;f 1234 /f 4567&lt;8.000  (4)
 
     In condition 4, if f1234/f567 is 0.800 or less, the refractive power of the front lens group composed of the first lens, the second lens, the third lens, and the fourth lens is excessively high, making it difficult to appropriately correct various aberrations. On the other hand, if f1234/f567 is 8.000 or greater, the refractive power of the front lens group composed of the first lens, the second lens, the third lens, and the fourth lens is excessively low, making it difficult to reduce the diameter of each lens of the front lens group and to miniaturize the wide-angle lens as a whole. 
     In contrast, in this embodiment, since condition 4 is satisfied, it is easy to appropriately correct various aberrations and to realize miniaturization. 
     In addition, in the wide-angle lens  1000 , the combined effective focal length f567 of the fifth lens  150 , the sixth lens  160 , and the seventh lens  170  is 3.374 mm, and the effective focal length f of the lens system as a whole is 1.019 mm. Therefore, the following condition 5 is satisfied: 
       2.800 &lt;f 567 /f&lt; 3.850  (5)
 
     In condition 5, if f567/f is 2.800 or less, the refractive power of the rear lens group composed of the fifth lens, the sixth lens, and the seventh lens is excessively high, making it difficult to appropriately correct various aberrations, especially chromatic aberration. On the other hand, if f567/f is 3.850 or greater, it is difficult to reduce the diameter of each lens and the object-to-image distance, thus making it difficult to miniaturize the wide-angle lens as a whole. 
     In contrast, in this embodiment, since condition 5 is satisfied, it is easy to appropriately correct various aberrations, especially chromatic aberration, and to realize miniaturization. 
     In summary, in this embodiment, by configuring the wide-angle lens  1000  as above, as shown in  FIG. 34A  to  FIG. 36L , it is easy to ensure the optical performance while preventing the overall length of the lens system from becoming excessively large. 
     The disclosure has been exemplarily described above with reference to the accompanying drawings, and it is obvious that the specific implementation of the disclosure is not limited by the foregoing embodiments. 
     For example, in the foregoing embodiments, the form of the first surface  1  of the first lens  110 , the form of the third surface  3  of the second lens  120 , the form of the fifth surface  5  of the third lens  130 , the form of the seventh surface  7  of the fourth lens  140 , and the form of the twelfth surface  12  of the sixth lens  160  may be appropriately changed as needed. 
     In addition, in the foregoing embodiments, the first lens  110  and the fifth lens  150  may be composed of plastic lenses, and the second lens  120 , the third lens  130 , the fourth lens  140 , the sixth lens  160  and the seventh lens  170  may be composed of glass lenses. 
     Features of the above-described preferred embodiments and the modifications thereof may be combined appropriately as long as no conflict arises. 
     While preferred embodiments of the present disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The scope of the present disclosure, therefore, is to be determined solely by the following claims.