Abstract:
This invention discloses an optical zoom lens assembly, sequentially arranged from an object side to an image side along an optical axis comprising: a first lens-group, a second lens-group and a third lens-group. The first lens-group with negative refractive power comprises at least one positive lens, and at least one negative lens. The second lens-group with positive refractive power comprises at least one positive lens, and at least one negative lens. The third lens-group with a positive refractive power comprises at least one aspheric lens. Therein, refractive indexes of the first lens-group, the second lens-group and the third lens-group are small than 1.69. Therefore, the present invention can reduce manufacturing costs and provide good image quality to be applied to cameras, cell phone cameras and other devices.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Taiwan Patent Application No.101118777, filed on May 25, 2012, in the Taiwan Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
     BACKGROUND OF THE INVENTION 
     1.Field of the Invention 
     The present invention relates to an optical zoom lens assembly, and more particularly to the optical zoom lens assembly comprised of three groups of plastic lenses and may apply in an electronic product. 
     2.Description of Related Art 
     In general, a zoom lens allows a user to capture a scene easily by changing a focal length at a same location. At the same time, the zoom lens can substitute a plurality of fixed lenses, so that the user needs not to carry many lenses for photography or spend much money on the lenses. Thereby, the zoom lens becomes a favorable tool to photographers. 
     However, the zoom lens generally comes with a complicated assembly and components, so that the zoom lens is usually large, heavy and long. To overcome the problems of the complicated assembly and components and a low image quality, the cost of the zoom lens has to become higher. 
     In order to provide a more practical design of the present invention, the lenses of the three lens-groups are made of plastic, so that the zoom lens can achieve the effects of maintaining a high-quality imaging capability, reducing the manufacturing cost, and being applicable in electronic products. 
     SUMMARY OF THE INVENTION 
     Therefore, it is a primary objective of the invention to provide an optical zoom lens assembly, sequentially arranged from an object side to an image side along an optical axis comprising: a first lens-group, a second lens-group and a third lens-group. The first lens-group with negative refractive power includes at least one positive lens and at least one negative lens. The second lens-group with positive refractive power includes at least one positive lens and at least one negative lens. The third lens-group with positive refractive power includes at least one aspherical surface. Wherein, the first lens-group, the second lens-group and the third lens-group have refractive indexes smaller than 1.69. The second lens-group has a focal length of f 2 , a third lens of the second lens-group has a focal length of f 21 , and the condition of 0.3&lt;f 21 /f 2 &lt;0.8 is satisfied. 
     Preferably, the first lens-group, sequentially arranged from an object side to an image side along an optical axis, may comprise a first lens and a second lens; the first lens with negative refractive power has a concave object-side surface and a concave image-side surface; and the second lens with positive refractive power has a convex object-side surface and a concave image-side surface. 
     Preferably, the image-side surface of the first lens, and the object-side surface or the image-side surface of the second lens are aspherical surfaces. 
     Preferably, the second lens-group, sequentially arranged from the object side to the image side along the optical axis, may comprise the third lens, a fourth lens and a fifth lens; the third lens with positive refractive power has a convex object-side surface and a convex image-side surface; the fourth lens with negative refractive power has a concave object-side surface and a concave image-side surface; and the fifth lens with negative refractive power has a convex object-side surface and a concave image-side surface. 
     Preferably, the object-side surface of the third lens or the object-side surface or the image-side surface of the fifth lens is an aspherical surface. 
     Preferably, the third lens-group may include a sixth lens with positive refractive power, having a concave object-side surface and a convex image-side surface. 
     Preferably, the object-side surface or the image-side surface of the sixth lens is an aspherical surface. 
     It is another objective of the present invention to provide an optical zoom lens assembly, sequentially arranged from an object side to an image side along an optical axis, comprising: a first lens-group, a second lens-group and a third lens-group. The first lens-group comprises: a first lens with negative refractive power, having a concave object-side surface and a concave image-side surface; and a second lens with positive refractive power, having a convex object-side surface and a concave image-side surface. The second lens-group comprises: a third lens with positive refractive power, having a convex object-side surface and a convex image-side surface; a fourth lens with negative refractive power, having a concave object-side surface and a concave image-side surface; and a fifth lens with negative refractive power, having a convex object-side surface and a concave image-side surface. The third lens-group comprises a sixth lens with positive refractive power, having a concave object-side surface and a convex image-side surface. Wherein, the first lens-group, the second lens-group and the third lens-group have refractive indexes smaller than 1.69; and the second lens-group has a focal length of f 2 , and the third lens has a focal length of f 21 , and the condition of 0.3&lt;f 21 /f 2 &lt;0.8 is satisfied. 
     Preferably, the first lens-group has negative refractive power, the second lens-group may have positive refractive power, and the third lens-group has positive refractive power. 
     Preferably, the image-side surface of the first lens, the object-side surface or the image-side surface of the second lens, the image-side surface of the third lens, the image-side surface of the fifth lens, and object-side surface or the image-side surface of the sixth lens are aspherical surfaces. 
     The lenses of the optical zoom lens assembly of the present invention are made of plastic and used to substitute the conventional zoom lenses made of glass, so as to facilitate the manufacture and lower the cost. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a first schematic view of an optical zoom lens assembly of the present invention; 
         FIG. 2  is a second schematic view of an optical zoom lens assembly of the present invention; 
         FIG. 3  is a third schematic view of an optical zoom lens assembly of the present invention; 
         FIG. 4  is an astigmatism curve of an optical zoom lens assembly of the present invention; 
         FIG. 5  is a distortion curve of an optical zoom lens assembly of the present invention; 
         FIG. 6  is a longitudinal aberration curve of an optical zoom lens assembly of the present invention; and 
         FIG. 7  is a lateral aberration curve of an optical zoom lens assembly of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The technical contents and characteristics of the present invention will be apparent with the detailed description of a preferred embodiment accompanied with related drawings as follows. For simplicity, the drawings are not necessarily drawn in actual scale or ratio, and same numerals are used in the following preferred embodiment to represent respective same elements. It is noteworthy that the drawings are provided for the purpose of illustrating the present invention, but not intended for limiting the scope of the invention. 
     The present invention provides an optical zoom lens assembly, sequentially arranged from an object side to an image side along an optical axis, comprising: a first lens-group, a second lens-group and a third lens-group. Wherein, the first lens-group with negative refractive power includes at least one positive lens and at least one negative lens. The second lens-group with positive refractive power includes at least one positive lens and at least one negative lens. The third lens-group with positive refractive power includes at least one aspherical surface. 
     With reference to  FIG. 1  for the first schematic view of an optical zoom lens assembly of the present invention, the first lens-group G 1  comprises a first lens  110  and a second lens  120 ; the second lens-group G 2  comprises a third lens  130 , a fourth lens  140  and a fifth lens  150 ; and the third lens-group G 3  comprises a sixth lens  160 . The optical zoom lens assembly, sequentially arranged from an object side to an image side along an optical axis, comprises: a first lens  110  with negative refractive power, made of plastic, having a concave object-side surface  111  and a concave image-side surface  112 ; a second lens  120  with positive refractive power, made of plastic, having a convex object-side surface  121  and a concave image-side surface  122 ; an aperture  100 ; a third lens  130  with positive refractive power, made of plastic, having a convex object-side surface  131  and a convex image-side surface  132 ; a fourth lens  140  with negative refractive power, made of plastic, having a concave object-side surface  141  and a concave image-side surface  142 ; a fifth lens  150  with negative refractive power, made of plastic, having a convex object-side surface  151  and a concave image-side surface  152 ; a sixth lens  160  with positive refractive power, made of plastic, having a concave object-side surface  161  and a convex image-side surface  162 ; and an infrared filter (IR-filter)  170  for adjusting a wavelength section of an image. With the assembly of the first lens-group G 1 , the second lens-group G 2 , the third lens-group G 3 , the aperture  100  and the IR-filter  170 , an image of an object to be photographed can be formed on an image plane  180 . 
     The optical zoom lens assembly comprises three lens-groups, the aperture  100  and the IR-filter  170 . The aperture  100  is situated between the first lens-group G 1  and the second lens-group G 2 . The IR-filter  170  is installed between the sixth lens  160  and the image plane  180  and generally made of an optical sheet material that does not affect the focal length of the optical zoom lens assembly of the present invention. 
     Wherein, one of the image-side surface  112  of the first lens  110 , the object-side surface  121  or the image-side surface  122  of the second lens  120 , the object-side surface  131  of the third lens  130 , the object-side surface  151  or the image-side surface  152  of the fifth lens  150 , and the object-side surface  161  or the image-side surface  162  of the sixth lens  160  or combinations thereof are aspherical surfaces, and the aforementioned lenses satisfies the aspherical surface formula as given in the following Equation (1): 
     
       
         
           
             
               
                 
                   
                     X 
                     ⁡ 
                     
                       ( 
                       Y 
                       ) 
                     
                   
                   = 
                   
                     
                       
                         ( 
                         
                           
                             Y 
                             2 
                           
                           / 
                           R 
                         
                         ) 
                       
                       
                         1 
                         + 
                         
                           
                             ( 
                             
                               1 
                               - 
                               
                                 
                                   ( 
                                   
                                     1 
                                     + 
                                     K 
                                   
                                   ) 
                                 
                                 ⁢ 
                                 
                                   
                                     ( 
                                     
                                       Y 
                                       / 
                                       R 
                                     
                                     ) 
                                   
                                   2 
                                 
                               
                             
                             ) 
                           
                         
                       
                     
                     + 
                     
                       
                         ∑ 
                         i 
                       
                       ⁢ 
                       
                         
                           ( 
                           
                             A 
                             i 
                           
                           ) 
                         
                         · 
                         
                           
                             ( 
                             
                               Y 
                               i 
                             
                             ) 
                           
                           . 
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
     wherein, X is the relative height of a point which has a distance Y from the aspherical surface from a tangent plane of the tip of the optical axis of the aspherical surface; 
     Y is the distance between a point on the curve of the aspherical surface and the optical axis; 
     R is the radius of curvature; 
     K is the conic coefficient; and 
     Ai is the i th  level aspherical surface coefficient. 
     In the optical zoom lens assembly of the present invention, the first lens  110 , the second lens  120 , the third lens  130 , the fifth lens  150  and the sixth lens  160  can be spherical surfaces or aspherical surfaces. For aspherical surfaces, the radius of curvature of the optical surface can be used for changing the refractive power to eliminate aberrations, so as to reduce the total length of the optical zoom lens assembly. 
     
       
         
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Optical Data of the First Schematic View 
               
               
                 f = 5.25 mm, Fno = 3.3 
               
             
          
           
               
                 Optical 
                 Lens- 
                   
                 Radius of 
                 Thickness or 
                 Refractive 
                 Abbe 
               
               
                 Surface 
                 Group 
                   
                 Curvature 
                 Distance(mm) 
                 Index 
                 No. 
               
               
                   
               
             
          
           
               
                 0 
                   
                 Object to be 
                   
                   
                   
                   
               
               
                   
                   
                 photographed 
                   
                   
                   
                   
               
               
                 1 
                 First 
                 First lens 
                 −34.165 
                 2 
                 1.530 
                 56.000 
               
               
                 2 
                 lens-group 
                   
                 4.81(ASP) 
                 2 
                   
                   
               
               
                 3 
                   
                 Second lens 
                 7.886(ASP) 
                 2.7 
                 1.600 
                 27.000 
               
               
                 4 
                   
                   
                 20.076(ASP) 
                 22.66 
                   
                   
               
               
                 5 
                   
                 Aperture 
                 ∞ 
                 0.3 
                   
                   
               
               
                 6 
                 Second 
                 Third lens 
                 4.947(ASP) 
                 2.7 
                 1.530 
                 56.000 
               
               
                 7 
                 lens-group 
                   
                 −9.789 
                 0.1 
                   
                   
               
               
                 8 
                   
                 Fourth lens 
                 −11.616 
                 0.6 
                 1.600 
                 27.000 
               
               
                 9 
                   
                   
                 13.073 
                 0.1 
                   
                   
               
               
                 10 
                   
                 Fifth lens 
                 4.0(ASP) 
                 0.6 
                 1.530 
                 56.000 
               
               
                 11 
                   
                   
                 3.659(ASP) 
                 4.07 
                   
                   
               
               
                 12 
                 Third 
                 Sixth lens 
                 −85.587(ASP) 
                 2.2 
                 1.530 
                 56.000 
               
               
                 13 
                 lens-group 
                   
                 −13.257(ASP) 
                 1.5 
                   
                   
               
               
                 14 
                   
                 IR-filter 
                 ∞ 
                 0.8 
                 1.516 
                 64.000 
               
               
                 15 
                   
                   
                 ∞ 
                 5.38 
               
               
                   
               
               
                 Note: 
               
               
                 ASP stands for aspherical surface. 
               
             
          
         
       
     
     With reference to Table 1, the optical zoom lens assembly has a focal length f=5.25 (mm), such that the overall aperture value (f-number) Fno=3.3. Wherein, the second lens-group G 2  has a focal length of f 2 , and a third lens  130  of the second lens-group G 2  has a focal length of f 21 , and the condition: 0.3&lt;f 21 /f 2 &lt;0.8 is satisfied. It is noteworthy that a material with a refractive index smaller than 1.69 is used to manufacturing the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , the fifth lens  150  and the sixth lens  160 , so as to lower the manufacturing cost. 
     Wherein, the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , the fifth lens  150  and to sixth lens  160  have object-side surface and image-side surface in compliance with the aspherical surface formula as given in Equation (1), and the aspherical coefficients are listed in Table 2. 
     
       
         
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Aspherical Coefficients 
               
             
          
           
               
                 Surface 
                 2 
                 3 
                 4 
                 6 
                 10 
                 11 
                 12 
               
               
                   
               
               
                 k= 
                 −5.390E−01 
                 −7.190E−01 
                   6.381E+00 
                 −2.890E−01 
                   1.370E−01 
                   2.040E−01 
                   9.429E+01 
               
               
                  A4= 
                 −7.630E−04 
                 −3.580E−04 
                 −3.930E−04 
                   3.560E−04 
                 −1.020E−03 
                   1.410E−03 
                 −3.527E−05 
               
               
                  A6= 
                 −3.321E−06 
                 −5.056E−06 
                 −2.746E−06 
                   1.613E−05 
                 −7.840E−04 
                 −9.480E−04  
                 −1.609E−05 
               
               
                  A8= 
                   4.942E−07 
                   7.184E−07 
                   4.233E−07 
                   8.332E−07 
                 −4.214E−07 
                   1.696E−05 
                 −4.350E−06 
               
               
                 A10= 
                 −1.204E−08 
                 −1.132E−08 
                 −9.173E−09 
                 −1.176E−07 
                 −4.668E−07 
                 −4.617E−06 
                   3.890E−07 
               
               
                 A12= 
                   
                   
                   
                   
                   
                   3.397E−07 
                 −1.052E−08 
               
               
                   
               
             
          
         
       
     
     Wherein, the first lens-group G 1 , the second lens-group G 2  and the third lens-group G 3  can be moved between the object side and the image side. 
     With reference to  FIG. 2  for the second schematic view of an optical zoom lens assembly of the present invention, the first lens-group G 1  comprises a first lens  210  and a second lens  220 , the second lens-group G 2  comprises a third lens  230 , a fourth lens  240  and a fifth lens  250 , and the third lens-group G 3  comprises a sixth lens  260 . The optical zoom lens assembly, sequentially arranged from an object side to an image side along an optical axis, comprises: a first lens  210  with negative refractive power, made of plastic, having a concave object-side surface  211  and a concave image-side surface  212 ; a second lens  220  with positive refractive power, made of plastic, having a convex object-side surface  221  and a concave image-side surface  222 ; an aperture  200 ; a third lens  230  with positive refractive power, made of plastic, having a convex object-side surface  231  and a convex image-side surface  232 ; a fourth lens  240  with negative refractive power, made of plastic, having a concave object-side surface  241  and a concave image-side surface  242 ; a fifth lens  250  with negative refractive power, made of plastic, having a convex object-side surface  251  and a concave image-side surface  252 ; a sixth lens  260  with positive refractive power, made of plastic, having a concave object-side surface  261  and a convex image-side surface  262 ; and an IR-filter  270 , for adjusting a wavelength section of an image. With the assembly of the first lens-group G 1 , the second lens-group G 2 , the third lens-group G 3 , the aperture  200  and the IR-filter  270 , an image of an object to be photographed can be formed on an image plane  280 . 
     The optical zoom lens assembly comprises three lens-groups, the aperture  200  and the IR-filter  270 . The aperture  200  is situated between the first lens-group G 1  and the second lens-group G 2 . The IR-filter  270  is installed between the sixth lens  260  and the image plane  280  and generally made of an optical sheet material that does not affect the focal length of the optical zoom lens assembly of the present invention. 
     In the optical zoom lens assembly of the present invention, the first lens  210 , the second lens  220 , the third lens  230 , the fifth lens  250  and the sixth lens  260  can be spherical surfaces or aspherical surfaces. For aspherical surfaces, the radius of curvature of the optical surfaces can be used for changing the refractive power to eliminate aberrations, so as to reduce the total length of the optical zoom lens assembly. 
     
       
         
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Optical Data of the Second Schematic View 
               
               
                 f = 11.2 mm, Fno = 4.76 
               
             
          
           
               
                 Optical 
                 Lens- 
                   
                 Radius of 
                 Thickness or  
                 Refractive 
                 Abbe 
               
               
                 Surface 
                 Group 
                   
                 Curvature 
                 Distance(mm) 
                 Index 
                 No. 
               
               
                   
               
             
          
           
               
                 0 
                   
                 Object to be 
                   
                   
                   
                   
               
               
                   
                   
                 photographed 
                   
                   
                   
                   
               
               
                 1 
                 First 
                 First lens 
                 −34.165 
                 2 
                 1.530 
                 56.000 
               
               
                 2 
                 lens-group 
                   
                 4.81(ASP) 
                 2 
                   
                   
               
               
                 3 
                   
                 Second lens 
                 7.886(ASP) 
                 2.7 
                 1.600 
                 27.000 
               
               
                 4 
                   
                   
                 20.076(ASP) 
                 8.753 
                   
                   
               
               
                 5 
                   
                 Aperture 
                 ∞ 
                 0.3 
                   
                   
               
               
                 6 
                 Second 
                 Third lens 
                 4.947(ASP) 
                 2.7 
                 1.530 
                 56.000 
               
               
                 7 
                 lens-group 
                   
                 −9.789 
                 0.1 
                   
                   
               
               
                 8 
                   
                 Fourth lens 
                 −11.616 
                 0.6 
                 1.600 
                 27.000 
               
               
                 9 
                   
                   
                 13.073 
                 0.1 
                   
                   
               
               
                 10 
                   
                 Fifth lens 
                 4.0(ASP) 
                 0.6 
                 1.530 
                 56.000 
               
               
                 11 
                   
                   
                 3.659(ASP) 
                 11.528 
                   
                   
               
               
                 12 
                 Third 
                 Sixth lens  
                 −85.587(ASP) 
                 2.2 
                 1.530 
                 56.000 
               
               
                 13 
                 lens-group 
                   
                 −13.257(ASP) 
                 1.5 
                   
                   
               
               
                 14 
                   
                 IR-filter 
                 ∞ 
                 0.8 
                 1.516 
                 64.000 
               
               
                 15 
                   
                   
                 ∞ 
                 5.38 
               
               
                   
               
               
                 Note: 
               
               
                 ASP stands for aspherical surface. 
               
             
          
         
       
     
     With reference to Table 3, the optical zoom lens assembly has a focal length f=11.2 (mm), such that the overall aperture value (f-number) Fno=4.76. Wherein, the second lens-group G 2  has a focal length of f 2 =13.18 (mm), and a third lens  230  of the second lens-group G 2  has a focal length of f 21 =6.4 (mm), and the condition: 0.3&lt;f 21 /f 2 &lt;0.8 is satisfied. It is noteworthy that a material with a refractive index smaller than 1.69 is used to manufacturing the first lens  210 , the second lens  220 , the third lens  230 , the fourth lens  240 , the fifth lens  250  and the sixth lens  260 , so as to lower the manufacturing cost. 
     Wherein, the first lens-group G 1 , the second lens-group G 2  and the third lens-group G 3  can be moved between the object side and the image side. 
     With reference to  FIG. 3  for the third schematic view of an optical zoom lens assembly of the present invention, the first lens-group G 1  comprises a first lens  310  and a second lens  320 , the second lens-group G 2  comprises a third lens  330 , a fourth lens  340  and a fifth lens  350 , and the third lens-group G 3  comprises a sixth lens  360 . The optical zoom lens assembly, sequentially arranged from an object side to an image side of an optical axis, comprises: a first lens  310  with negative refractive power, made of plastic, having a concave object-side surface  311  and a concave image-side surface  312 ; a second lens  320  with positive refractive power, made of plastic, having a convex object-side surface  321  and a concave image-side surface  322 ; an aperture  300 ; a third lens  330  with positive refractive power, made of plastic, having a convex object-side surface  331  and a convex image-side surface  332 ; a fourth lens  340  with negative refractive power, made of plastic, having a concave object-side surface  341  and a concave image-side surface  342 ; a fifth lens  350  with negative refractive power, made of plastic, having a convex object-side surface  351  and a concave image-side surface  352 ; a sixth lens  360  with positive refractive power, made of plastic, having a concave object-side surface  361  and a convex image-side surface  362 ; and an IR-filter  370 , for adjusting a wavelength section of an image. With the assembly of the first lens-group G 1 , the second lens-group G 2 , the third lens-group G 3 , the aperture  300  and the IR-filter  370 , an image of an object to be photographed can be formed on an image plane  380 . 
     The optical zoom lens assembly comprises three lens-groups, the aperture  300  and the IR-filter  370 . The aperture  300  is situated between the first lens-group G 1  and the second lens-group G 2 . The IR-filter  370  is installed between the sixth lens  360  and the image plane  380  and generally made of an optical sheet material that does not affect the focal length of the optical zoom lens assembly of the present invention. 
     In the optical zoom lens assembly of the present invention, the first lens  310 , the second lens  320 , the third lens  330 , the fifth lens  350  and the sixth lens  360  can be spherical surfaces or aspherical surfaces. For aspherical surfaces, the radius of curvature of the optical surface can be used for changing the refractive power to eliminate aberrations, so as to reduce the total length of the optical zoom lens assembly. 
     
       
         
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 Optical Data of the Third Schematic View 
               
               
                 f = 25 mm, Fno = 8.2 
               
             
          
           
               
                 Optical 
                 Lens- 
                   
                 Radius of 
                 Thickness or 
                 Refractive 
                 Abbe 
               
               
                 Surface 
                 Group 
                   
                 Curvature 
                 Distance(mm) 
                 Index 
                 No. 
               
               
                   
               
             
          
           
               
                 0 
                   
                 Object to be 
                   
                   
                   
                   
               
               
                   
                   
                 photographed 
                   
                   
                   
                   
               
               
                 1 
                 First 
                 First lens 
                 −34.165 
                 2 
                 1.530 
                 56.000 
               
               
                 2 
                 lens-group 
                   
                 4.81(ASP) 
                 2 
                   
                   
               
               
                 3 
                   
                 Second lens 
                 7.886(ASP) 
                 2.7 
                 1.600 
                 27.000 
               
               
                 4 
                   
                   
                 20.076(ASP) 
                 2.476 
                   
                   
               
               
                 5 
                   
                 Aperture 
                 ∞ 
                 0.3 
                   
                   
               
               
                 6 
                 Second 
                 Third lens 
                 4.947(ASP) 
                 2.7 
                 1.530 
                 56.000 
               
               
                 7 
                 lens-group 
                   
                 −9.789 
                 0.1 
                   
                   
               
               
                 8 
                   
                   
                 −11.616 
                 0.6 
                 1.600 
                 27.000 
               
               
                 9 
                   
                 Fourth lens 
                 13.073 
                 0.1 
                   
                   
               
               
                 10 
                   
                   
                 4.0(ASP) 
                 0.6 
                 1.530 
                 56.000 
               
               
                 11 
                   
                 Fifth lens 
                 3.659(ASP) 
                 29.142 
                   
                   
               
               
                 12 
                 Third 
                   
                 −85.587(ASP) 
                 2.2 
                 1.530 
                 56.000 
               
               
                 13 
                 lens-group 
                 Sixth lens 
                 −13.257(ASP) 
                 1.5 
                   
                   
               
               
                 14 
                   
                 IR-filter 
                 ∞ 
                 0.8 
                 1.516 
                 64.000 
               
               
                 15 
                   
                   
                 ∞ 
                 5.38 
               
               
                   
               
               
                 Note: 
               
               
                 ASP stands for aspherical surface. 
               
             
          
         
       
     
     With reference to Table 4, the optical zoom lens assembly has a focal length f=25 (mm), such that the overall aperture value (f-number) Fno=8.2. Wherein, the second lens-group G 2  has a focal length of f 2 , and a third lens  330  of the second lens-group G 2  has a focal length of f 21 , and the condition: 0.3&lt;f 21 /f 2 &lt;0.8 is satisfied. It is noteworthy that a material with a refractive index smaller than 1.69 is used to manufacturing the first lens  310 , the second lens  320 , the third lens  330 , the fourth lens  340 , the fifth lens  350  and the sixth lens  360 , so as to lower the manufacturing cost. 
     Wherein, the first lens-group G 1 , the second lens-group G 2  and the third lens-group G 3  are moved between the object side and the image side. 
     With reference to  FIG. 4  for the astigmatism curve of an optical zoom lens assembly of the present invention, the optical zoom lens assembly has a variable focal length ranging from 5 mm to 25 mm, and an overall aperture value (f-number) Fno ranging from 3.3 to 8.5, so that the maximum TTL value of the distance from the object-side surface of the first lens to the image plane on the optical axis is equal to 54 mm. If the distance between the first lens-group and the second lens-group is equal to 22.66 mm, and the distance between the second lens-group and the third lens-group is equal to 4.07 mm, then a wide-angle end is defined; and if the distance between the first lens-group and the second lens-group is equal to 2.476 mm, and the distance between the second lens-group  30  and the third lens-group  40  is equal to 29.142, then a tele end is defined. 
     In addition, the first lens-group  20  adopts negative refractive power to increase the field of view, and after the first lens-group  20  is combined with the second lens-group  30  with the positive refractive power, the magnification of the image can be increased to enhance the resolution. The third lens-group  40  adopts positive, refractive power to effectively compensate the aberration produced by the first lens-group  20  and the second lens-group  30 , such that the aberration and distortion can meet the resolution requirements. 
     According to Tables 1 to 4 and  FIGS. 4 to 7 , the optical zoom lens assembly of the present invention provides good correction results in aspects of the field curving, distortion, longitudinal spherical aberration and lateral aberration. 
     Tables 1 to 4 show changes of values of an optical zoom lens assembly in accordance with different preferred embodiments of the present invention respectively, and even if different values are used, products of the same structure are intended to be covered by the scope of the present invention. It is noteworthy to point out that the aforementioned description and the illustration of related drawings are provided for the purpose of explaining the technical characteristics of the present invention, but not intended for limiting the scope of the present invention.