Patent Publication Number: US-2022236545-A1

Title: Zoom optical system, optical apparatus, imaging apparatus and method for manufacturing the zoom optical system

Description:
TECHNICAL FIELD 
     The present invention relates to a zoom optical system, an optical apparatus and an imaging apparatus including the same, and a method for manufacturing the zoom optical system. 
     TECHNICAL BACKGROUND 
     Conventionally, zoom optical systems suitable for photographic cameras, electronic still cameras, video cameras and the like have been proposed (for example, see Patent literature 1). 
     PRIOR ARTS LIST 
     Patent Document 
     
         
         Patent literature 1: Japanese Laid-Open Patent Publication No. H4-293007(A) 
       
    
     Unfortunately, according to the conventional zoom optical system, reduction in the weight of a focusing lens group is insufficient. 
     SUMMARY OF THE INVENTION 
     A zoom optical system according to the present invention comprises, in order from an object: a front lens group having a positive refractive power; an M1 lens group having a negative refractive power; an M2 lens group having a positive refractive power; and an RN lens group having a negative refractive power, wherein upon zooming, a distance between the front lens group and the M1 lens group changes, a distance between the M1 lens group and the M2 lens group changes, and a distance between the M2 lens group and the RN lens group changes, upon focusing from an infinite distant object to a short distant object, the RN lens group moves, and the M2 lens group comprises an A lens group that satisfies a following conditional expression, 
     
       
         
           
             1.10 
             &lt; 
             
               fvr 
               ⁢ 
               
                 / 
               
               ⁢ 
               fTM 
               ⁢ 
               
                   
               
               ⁢ 
               2 
             
             &lt; 
             2.00 
           
         
       
     
     where 
     fvr: a focal length of the A lens group, and 
     fTM2: a focal length of the M2 lens group in a telephoto end state. 
     An optical apparatus according to the present invention comprises the zoom optical system. 
     An imaging apparatus according to the present invention comprises: the zoom optical system; and an imaging unit that takes an image formed by the zoom optical system. 
     A method for manufacturing a zoom optical system according to the present invention is a method for manufacturing a zoom optical system comprising, in order from an object, a front lens group having a positive refractive power, an M1 lens group having a negative refractive power, an M2 lens group having a positive refractive power, and an RN lens group having a negative refractive power, the method comprising achieving an arrangement where upon zooming, a distance between the front lens group and the M1 lens group changes, a distance between the M1 lens group and the M2 lens group changes, and a distance between the M2 lens group and the RN lens group changes, wherein upon focusing from an infinite distant object to a short distant object, the RN lens group moves, and the M2 lens group comprises an A lens group that satisfies a following conditional expression, 
     
       
         
           
             1.10 
             &lt; 
             
               fvr 
               ⁢ 
               
                 / 
               
               ⁢ 
               fTM 
               ⁢ 
               
                   
               
               ⁢ 
               2 
             
             &lt; 
             2.00 
           
         
       
     
     where 
     fvr: a focal length of the A lens group, and 
     fTM2: a focal length of the M2 lens group in a telephoto end state. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a lens configuration of a zoom optical system according to a first example of this embodiment; 
         FIG. 2A  is graphs showing various aberrations of the zoom optical system according to the first example upon focusing on infinity in the wide-angle end state, and  FIG. 2B  is graphs showing meridional lateral aberrations (coma aberrations) when blur correction is applied to a rotational blur by 0.30°; 
         FIG. 3  is graphs showing various aberrations of the zoom optical system according to the first example upon focusing on infinity in the intermediate focal length state; 
         FIG. 4A  is graphs showing various aberrations of the zoom optical system according to the first example upon focusing on infinity in the telephoto end state, and  FIG. 4B  is graphs showing meridional lateral aberrations when blur correction is applied to a rotational blur by 0.20°; 
         FIGS. 5A, 5B and 5C  are graphs showing various aberrations of the zoom optical system according to the first example upon focusing on a short distant object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively; 
         FIG. 6  shows a lens configuration of a zoom optical system according to a second example of this embodiment; 
         FIG. 7A  is graphs showing various aberrations of the zoom optical system according to the second example upon focusing on infinity in the wide-angle end state, and  FIG. 7B  is graphs showing meridional lateral aberrations when blur correction is applied to a rotational blur by 0.30°; 
         FIG. 8  is graphs showing various aberrations of the zoom optical system according to the second example upon focusing on infinity in the intermediate focal length state; 
         FIG. 9A  is graphs showing various aberrations of the zoom optical system according to the second example upon focusing on infinity in the telephoto end state, and  FIG. 9B  is graphs showing meridional lateral aberrations when blur correction is applied to a rotational blur by 0.20°; 
         FIGS. 10A, 10B and 10C  are graphs showing various aberrations of the zoom optical system according to the second example upon focusing on a short distant object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively; 
         FIG. 11  shows a lens configuration of a zoom optical system according to a third example of this embodiment; 
         FIG. 12A  is graphs showing various aberrations of the zoom optical system according to the third example upon focusing on infinity in the wide-angle end state, and  FIG. 12B  is graphs showing meridional lateral aberrations when blur correction is applied to a rotational blur by 0.30°; 
         FIG. 13  is graphs showing various aberrations of the zoom optical system according to the third example upon focusing on infinity in the intermediate focal length state; 
         FIG. 14A  is graphs showing various aberrations of the zoom optical system according to the third example upon focusing on infinity in the telephoto end state, and  FIG. 14B  is graphs showing meridional lateral aberrations when blur correction is applied to a rotational blur by 0.20°; 
         FIGS. 15A, 15B and 15C  are graphs showing various aberrations of the zoom optical system according to the third example upon focusing on a short distant object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively; 
         FIG. 16  shows a lens configuration of a zoom optical system according to a fourth example of this embodiment; 
         FIG. 17A  is graphs showing various aberrations of the zoom optical system according to the fourth example upon focusing on infinity in the wide-angle end state, and  FIG. 17B  is graphs showing meridional lateral aberrations when blur correction is applied to a rotational blur by 0.30°; 
         FIG. 18  is graphs showing various aberrations of the zoom optical system according to the fourth example upon focusing on infinity in the intermediate focal length state; 
         FIG. 19A  is graphs showing various aberrations of the zoom optical system according to the fourth example upon focusing on infinity in the telephoto end state, and  FIG. 19B  is graphs showing meridional lateral aberrations when blur correction is applied to a rotational blur by 0.20°; 
         FIGS. 20A, 20B and 20C  are graphs showing various aberrations of the zoom optical system according to the fourth example upon focusing on a short distant object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively; 
         FIG. 21  shows a lens configuration of a zoom optical system according to a fifth example of this embodiment; 
         FIG. 22A  is graphs showing various aberrations of the zoom optical system according to the fifth example upon focusing on infinity in the wide-angle end state, and  FIG. 22B  is graphs showing meridional lateral aberrations when blur correction is applied to a rotational blur by 0.30°; 
         FIG. 23  is graphs showing various aberrations of the zoom optical system according to the fifth example upon focusing on infinity in the intermediate focal length state; 
         FIG. 24A  is graphs showing various aberrations of the zoom optical system according to the fifth example upon focusing on infinity in the telephoto end state, and  FIG. 24B  is graphs showing meridional lateral aberrations when blur correction is applied to a rotational blur by 0.20°; 
         FIGS. 25A, 25B and 25C  are graphs showing various aberrations of the zoom optical system according to the fifth example upon focusing on a short distant object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively; 
         FIG. 26  shows a configuration of a camera comprising a zoom optical system according to this embodiment; and 
         FIG. 27  is a flowchart showing a method for manufacturing the zoom optical system according to this embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, a zoom optical system, an optical apparatus, and an imaging apparatus of this embodiment are described with reference to the drawings. As shown in  FIG. 1 , a zoom optical system ZL( 1 ) that is an example of a zoom optical system (zoom lens) ZL according to this embodiment comprises, in order from an object: a front lens group GFS having a positive refractive power; an M1 lens group GM 1  having a negative refractive power; an M2 lens group GM 2  having a positive refractive power; and an RN lens group GRN having a negative refractive power, wherein upon zooming, a distance between the front lens group GFS and the M1 lens group GM 1  changes, a distance between the M1 lens group GM 1  and the M2 lens group GM 2  changes, and a distance between the M2 lens group GM 2  and the RN lens group GRN changes, upon focusing from an infinite distant object to a short distant object, the RN lens group GRN moves, and the M2 lens group GM 2  comprises an A lens group that satisfies a following conditional expression (1), 
     
       
         
           
             
               
                 
                   1.10 
                   &lt; 
                   
                     fvr 
                     ⁢ 
                     
                       / 
                     
                     ⁢ 
                     fTM 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     2 
                   
                   &lt; 
                   2.00 
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
     where 
     fvr: a focal length of the A lens group, and 
     fTM2: a focal length of the M2 lens group GM 2  in a telephoto end state. 
     The zoom optical system ZL according to this embodiment may be a zoom optical system ZL( 2 ) shown in  FIG. 6 , a zoom optical system ZL( 3 ) shown in  FIG. 11 , a zoom optical system ZL( 4 ) shown in  FIG. 16 , or a zoom optical system ZL( 5 ) shown in  FIG. 21 . 
     The zoom optical system of this embodiment includes at least four lens groups, and changes the distances between lens groups upon zooming from the wide-angle end state to the telephoto end state, thereby allowing favorable aberration correction upon zooming to be facilitated. Focusing with the RN lens group GRN can reduce the size and weight of the RN lens group GRN, that is, the focusing lens group. 
     The conditional expression (1) defines the ratio of the focal length of the A lens group to the focal length of the M2 lens group GM 2  in the telephoto end state. By satisfying the conditional expression (1), variation in various aberrations including the spherical aberration upon zooming from the wide-angle end to the telephoto end can be suppressed, and occurrence of various aberrations including the decentering coma aberration upon blur correction can be suppressed. 
     If the corresponding value of the conditional expression (1) of the zoom optical system of this embodiment exceeds the upper limit value, the refractive power of the M2 lens group GM 2  in the telephoto end state becomes strong, and it is difficult to suppress variation in various aberrations including the spherical aberration upon zooming from the wide-angle end to the telephoto end. Note that setting of the upper limit value of the conditional expression (1) to 1.95 can more securely achieve the advantageous effects of this embodiment. To further secure the advantageous effects of this embodiment, it is preferable that the upper limit value of the conditional expression (1) be 1.90. 
     If the corresponding value of the conditional expression (1) of the zoom optical system of this embodiment falls below the lower limit value, the refractive power of the A lens group becomes strong, and it becomes difficult to suppress occurrence of various aberrations including the decentering coma aberration upon blur correction. Note that setting of the lower limit value of the conditional expression (1) to 1.15 can more securely achieve the advantageous effects of this embodiment. To further secure the advantageous effects of this embodiment, it is preferable that the lower limit value of the conditional expression (1) be 1.20. 
     According to the zoom optical system of this embodiment, reduction in size and weight of the focusing lens group can achieve high-speed AF and silence during AF without increasing the size of the lens barrel. Furthermore, variation of aberrations upon zooming from the wide-angle end state to the telephoto end state, and variation of aberrations upon focusing from an infinite distant object to a short distant object can be favorably suppressed. The optical apparatus, the imaging apparatus, and the method for manufacturing the zoom optical system according to this embodiment can also achieve analogous advantageous effects. 
     In the zoom optical system according to this embodiment, preferably, upon zooming from a wide-angle end state to a telephoto end state, the front lens group GFS moves toward the object. Accordingly, the entire length of the lens at the wide-angle end state can be reduced, which can facilitate reduction in the size of the zoom optical system. 
     In the zoom optical system according to this embodiment, preferably, upon zooming from a wide-angle end state to a telephoto end state, a lens group nearest to the object in the M1 lens group GM 1  is fixed with respect to an image surface. Accordingly, degradation in performance due to manufacturing errors is suppressed, which can secure mass-productivity. 
     In the zoom optical system according to this embodiment, preferably, the A lens group consists of, in order from the object: a lens having a negative refractive power; and a lens having a positive refractive power. 
     It is desirable that the zoom optical system of this embodiment comprising the A lens group satisfy a following conditional expression (2), 
     
       
         
           
             
               
                 
                   
                     1. 
                     ⁢ 
                     
                       0 
                       ⁢ 
                       0 
                     
                   
                   &lt; 
                   
                     nvrN 
                     ⁢ 
                     
                       / 
                     
                     ⁢ 
                     nvrP 
                   
                   &lt; 
                   1.25 
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
     
     where 
     nvrN: a refractive index of the lens having the negative refractive power in the A lens group, and 
     nvrP: a refractive index of the lens having the positive refractive power in the A lens group. 
     The conditional expression (2) defines the ratio of the refractive index of the lens that is in the A lens group and has the negative refractive power to the refractive index of the lens that is in the A lens group and has the positive refractive power. By satisfying the conditional expression (2), degradation in performance upon blur correction by the A lens group can be effectively suppressed. 
     If the corresponding value of the conditional expression (2) exceeds the upper limit value, the refractive index of the lens that is in the A lens group and has a positive refractive power decreases, the decentering coma aberration caused upon blur correction excessively occurs, and it becomes difficult to correct the aberration. Setting of the upper limit value of the conditional expression (2) to 1.22 can more securely achieve the advantageous effects of this embodiment. To further secure the advantageous effects of this embodiment, it is preferable that the upper limit value of the conditional expression (2) be 1.20. 
     If the corresponding value of the conditional expression (2) falls below the lower limit value, the refractive index of the lens that is in the A lens group and has the negative refractive power becomes low, and it becomes difficult to correct the decentering coma aberration upon blur correction. Setting of the lower limit value of the conditional expression (2) to 1.03 can more securely achieve the advantageous effects of this embodiment. To further secure the advantageous effects of this embodiment, it is preferable that the lower limit value of the conditional expression (2) be 1.05. 
     It is also desirable that the zoom optical system comprising the A lens group satisfy a following conditional expression (3), 
     
       
         
           
             
               
                 
                   0.30 
                   &lt; 
                   
                     vvrN 
                     ⁢ 
                     
                       / 
                     
                     ⁢ 
                     vvrP 
                   
                   &lt; 
                   0.90 
                 
               
               
                 
                   ( 
                   3 
                   ) 
                 
               
             
           
         
       
     
     where 
     νvrN: an Abbe number of the lens having the negative refractive power in the A lens group, and 
     νvrP: an Abbe number of the lens having the positive refractive power in the A lens group. 
     The conditional expression (3) defines the ratio of the Abbe number of the lens that is in the A lens group and has a negative refractive power to the Abbe number of the lens that is in the A lens group and has a positive refractive power. By satisfying the conditional expression (3), degradation in performance upon blur correction can be effectively suppressed. 
     If the corresponding value of the conditional expression (3) exceeds the upper limit value, the Abbe number of the lens that is in the A lens group and has the positive refractive power decreases, and it becomes difficult to correct the chromatic aberration caused upon blur correction. Setting of the upper limit value of the conditional expression (3) to 0.85 can more securely achieve the advantageous effects of this embodiment. To further secure the advantageous effects of this embodiment, it is preferable that the upper limit value of the conditional expression (3) be 0.80. 
     If the corresponding value of the conditional expression (3) falls below the lower limit value, the Abbe number of the lens that is in the A lens group and has a negative refractive power decreases, and it becomes difficult to correct the chromatic aberration caused upon blur correction. Setting of the lower limit value of the conditional expression (3) to 0.35 can more securely achieve the advantageous effects of this embodiment. To further secure the advantageous effects of this embodiment, it is preferable that the lower limit value of the conditional expression (3) be 0.40. 
     It is desirable that the zoom optical system according to this embodiment satisfy a following conditional expression (4), 
     
       
         
           
             
               
                 
                   0.15 
                   &lt; 
                   
                     
                       ( 
                       
                         
                           - 
                           fTM 
                         
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         1 
                       
                       ) 
                     
                     ⁢ 
                     
                       / 
                     
                     ⁢ 
                     f 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     1 
                   
                   &lt; 
                   0.35 
                 
               
               
                 
                   ( 
                   4 
                   ) 
                 
               
             
           
         
       
     
     where 
     fTM1: a focal length of the M1 lens group GM 1  in a telephoto end state, and 
     f1: a focal length of the front lens group GFS. 
     The conditional expression (4) defines the ratio of the focal length of the M1 lens group GM 1  to the focal length of the front lens group GFS in the telephoto end state. By satisfying the conditional expression (4), various aberrations including the spherical aberration upon zooming from the wide-angle end to the telephoto end can be suppressed. 
     If the corresponding value of the conditional expression (4) exceeds the upper limit value, the refractive power of the front lens group GFS becomes strong, and it is difficult to correct various aberrations including the spherical aberration upon zooming from the wide-angle end to the telephoto end. Setting of the upper limit value of the conditional expression (4) to 0.33 can more securely achieve the advantageous effects of this embodiment. To further secure the advantageous effects of this embodiment, it is preferable that the upper limit value of the conditional expression (4) be 0.31. 
     If the corresponding value of the conditional expression (4) falls below the lower limit value, the refractive power of the M1 lens group GM 1  becomes strong, and it is difficult to suppress variation in various aberrations including the spherical aberration upon zooming from the wide-angle end to the telephoto end. Setting of the lower limit value of the conditional expression (4) to 0.16 can more securely achieve the advantageous effects of this embodiment. To further secure the advantageous effects of this embodiment, it is preferable that the lower limit value of the conditional expression (4) be 0.17. 
     It is desirable that the zoom optical system according to this embodiment satisfy a following conditional expression (5), 
     
       
         
           
             
               
                 
                   0.20 
                   &lt; 
                   
                     fTM 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     2 
                     ⁢ 
                     
                       / 
                     
                     ⁢ 
                     f 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     1 
                   
                   &lt; 
                   0.40 
                 
               
               
                 
                   ( 
                   5 
                   ) 
                 
               
             
           
         
       
     
     where 
     f1: a focal length of the front lens group GFS. 
     The conditional expression (5) defines the ratio of the focal length of the M2 lens group GM 2  to the focal length of the front lens group GFS in the telephoto end state. By satisfying the conditional expression (5), various aberrations including the spherical aberration upon zooming from the wide-angle end to the telephoto end can be suppressed. 
     If the corresponding value of the conditional expression (5) exceeds the upper limit value, the refractive power of the front lens group GFS becomes strong, and it is difficult to correct various aberrations including the spherical aberration upon zooming from the wide-angle end to the telephoto end. Setting of the upper limit value of the conditional expression (5) to 0.37 can more securely achieve the advantageous effects of this embodiment. To further secure the advantageous effects of this embodiment, it is preferable that the upper limit value of the conditional expression (5) be 0.34. 
     If the corresponding value of the conditional expression (5) falls below the lower limit value, the refractive power of the M2 lens group GM 2  becomes strong, and it is difficult to suppress variation in various aberrations including the spherical aberration upon zooming from the wide-angle end to the telephoto end. Setting of the lower limit value of the conditional expression (5) to 0.22 can more securely achieve the advantageous effects of this embodiment. To further secure the advantageous effects of this embodiment, it is preferable that the lower limit value of the conditional expression (5) be 0.24. 
     In the zoom optical system according to this embodiment, preferably, the A lens group is a vibration-proof lens group movable in a direction orthogonal to an optical axis to correct an imaging position displacement due to a camera shake or the like. Accordingly, degradation in performance upon blur correction can be effectively suppressed. 
     Preferably, the zoom optical system according to this embodiment further comprises a negative meniscus lens that has a concave surface facing the object, which is provided contiguous to the RN lens group on an image side. The configuration may further comprise, in order from the object: a lens having a negative refractive power; and a lens having a positive refractive power, which are provided contiguous to the RN lens group on an image side. Accordingly, various aberrations including the coma aberration can be effectively corrected. 
     It is preferable that the zoom optical system according to this embodiment satisfy a following conditional expression (6), 
     
       
         
           
             
               
                 
                   
                     0. 
                     ⁢ 
                     
                       7 
                       ⁢ 
                       0 
                     
                   
                   &lt; 
                   
                     
                       ( 
                       
                         - 
                         fN 
                       
                       ) 
                     
                     ⁢ 
                     
                       / 
                     
                     ⁢ 
                     fP 
                   
                   &lt; 
                   
                     
                       2 
                       . 
                       0 
                     
                     ⁢ 
                     0 
                   
                 
               
               
                 
                   ( 
                   6 
                   ) 
                 
               
             
           
         
       
     
     where 
     fN: a focal length of a lens having a strongest negative refractive power among lenses adjacent to the image side of the RN lens group GRN, and 
     fP: a focal length of a lens having a strongest positive refractive power among lenses adjacent to the image side of the RN lens group GRN. 
     The conditional expression (6) described above defines the ratio of the focal length of the lens that has the strongest negative refractive power among the lenses adjacent to the image side of the RN lens group GRN to the focal length of the lens that has the strongest positive refractive power among the lenses adjacent to the image side of the RN lens group GRN. By satisfying the conditional expression (6), various aberrations including the coma aberration can be effectively corrected. 
     If the corresponding value of the conditional expression (6) exceeds the upper limit value, the refractive power of the lens that is disposed to the image side of the focusing lens group and has a positive refractive power becomes strong, and the coma aberration occurs excessively. Setting of the upper limit value of the conditional expression (6) to 1.90 can more securely achieve the advantageous effects of this embodiment. To further secure the advantageous effects of this embodiment, it is preferable that the upper limit value of the conditional expression (6) be 1.80. 
     If the corresponding value of the conditional expression (6) falls below the lower limit value, the refractive power of the lens that is disposed to the image side of the focusing lens group and has a negative refractive power becomes strong, and the coma aberration is excessively corrected. Setting of the lower limit value of the conditional expression (6) to 0.80 can more securely achieve the advantageous effects of this embodiment. To further secure the advantageous effects of this embodiment, it is preferable that the lower limit value of the conditional expression (6) be 0.90. 
     It is preferable that the zoom optical system according to this embodiment satisfy a following conditional expression (7), 
     
       
         
           
             
               
                 
                   
                     1. 
                     ⁢ 
                     80 
                   
                   &lt; 
                   
                     f 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     1 
                     ⁢ 
                     
                       / 
                     
                     ⁢ 
                     fw 
                   
                   &lt; 
                   
                     
                       3 
                       . 
                       5 
                     
                     ⁢ 
                     0 
                   
                 
               
               
                 
                   ( 
                   7 
                   ) 
                 
               
             
           
         
       
     
     where 
     fw: a focal length of the zoom optical system in a wide-angle end state, and 
     f1: a focal length of the front lens group GFS. 
     The conditional expression (7) defines the ratio of the focal length of the front lens group GFS to the focal length of the zoom optical system in the wide-angle end state. By satisfying the conditional expression (7), the size of the lens barrel can be prevented from increasing, and various aberrations including the spherical aberration upon zooming from the wide-angle end to the telephoto end can be suppressed. 
     If the corresponding value of the conditional expression (7) exceeds the upper limit value, the refractive power of the front lens group GFS becomes weak, and the size of lens barrel increases. Setting of the upper limit value of the conditional expression (7) to 3.30 can more securely achieve the advantageous effects of this embodiment. To further secure the advantageous effects of this embodiment, it is preferable to set the upper limit value of the conditional expression (7) to 3.10. 
     If the corresponding value of the conditional expression (7) falls below the lower limit value, the refractive power of the front lens group GFS becomes strong, and it is difficult to correct various aberrations including the spherical aberration upon zooming from the wide-angle end to the telephoto end. Setting of the lower limit value of the conditional expression (7) to 1.90 can more securely achieve the advantageous effects of this embodiment. To further secure the advantageous effects of this embodiment, it is preferable to set the lower limit value of the conditional expression (7) to 2.00, and it is more preferable to set the lower limit value of the conditional expression (7) to 2.10. 
     It is preferable that the zoom optical system according to this embodiment satisfy a following conditional expression (8), 
     
       
         
           
             
               
                 
                   
                     3. 
                     ⁢ 
                     70 
                   
                   &lt; 
                   
                     f 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     1 
                     ⁢ 
                     
                       / 
                     
                     ⁢ 
                     
                       ( 
                       
                         
                           - 
                           fTM 
                         
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         1 
                       
                       ) 
                     
                   
                   &lt; 
                   5.00 
                 
               
               
                 
                   ( 
                   8 
                   ) 
                 
               
             
           
         
       
     
     where 
     fTM1: a focal length of the M1 lens group GM 1  in a telephoto end state, and 
     f1: a focal length of the front lens group GFS. 
     The conditional expression (8) defines the ratio of the focal length of the front lens group GFS to the focal length of the M1 lens group GM 1 . By satisfying the conditional expression (8), various aberrations including the spherical aberration upon zooming from the wide-angle end to the telephoto end can be suppressed. 
     If the corresponding value of the conditional expression (8) exceeds the upper limit value, the refractive power of the M1 lens group GM 1  becomes strong, and it is difficult to suppress variation in various aberrations including the spherical aberration upon zooming from the wide-angle end to the telephoto end. Setting of the upper limit value of the conditional expression (8) to 4.90 can more securely achieve the advantageous effects of this embodiment. To further secure the advantageous effects of this embodiment, it is preferable to set the upper limit value of the conditional expression (8) to 4.80. 
     If the corresponding value of the conditional expression (8) falls below the lower limit value, the refractive power of the front lens group GFS becomes strong, and it is difficult to correct various aberrations including the spherical aberration upon zooming from the wide-angle end to the telephoto end. Setting of the lower limit value of the conditional expression (8) to 3.90 can more securely achieve the advantageous effects of this embodiment. To further secure the advantageous effects of this embodiment, it is preferable to set the lower limit value of the conditional expression (8) to 3.95. 
     It is preferable that the zoom optical system according to this embodiment satisfy a following conditional expression (9) 
     
       
         
           
             
               
                 
                   3.20 
                   &lt; 
                   
                     f 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     1 
                     ⁢ 
                     
                       / 
                     
                     ⁢ 
                     fTM 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     2 
                   
                   &lt; 
                   5.00 
                 
               
               
                 
                   ( 
                   9 
                   ) 
                 
               
             
           
         
       
     
     where 
     f1: a focal length of the front lens group GFS. 
     The conditional expression (9) defines the ratio of the focal length of the front lens group GFS to the focal length of the M2 lens group GM 2 . By satisfying the conditional expression (9), various aberrations including the spherical aberration upon zooming from the wide-angle end to the telephoto end can be suppressed. 
     If the corresponding value of the conditional expression (9) exceeds the upper limit value, the refractive power of the M2 lens group GM 2  becomes strong, and it is difficult to suppress variation in various aberrations including the spherical aberration upon zooming from the wide-angle end to the telephoto end. Setting of the upper limit value of the conditional expression (9) to 4.80 can more securely achieve the advantageous effects of this embodiment. To further secure the advantageous effects of this embodiment, it is preferable to set the upper limit value of the conditional expression (9) to 4.60. 
     If the corresponding value of the conditional expression (9) falls below the lower limit value, the refractive power of the front lens group GFS becomes strong, and it is difficult to correct various aberrations including the spherical aberration upon zooming from the wide-angle end to the telephoto end. Setting of the lower limit value of the conditional expression (9) to 3.40 can more securely achieve the advantageous effects of this embodiment. To further secure the advantageous effects of this embodiment, it is preferable to set the lower limit value of the conditional expression (9) to 3.60. 
     An optical apparatus and an imaging apparatus according to this embodiment comprise the zoom optical system having the configuration described above. As a specific example, a camera (corresponding to the imaging apparatus of the invention of the present application) including the aforementioned zoom optical system ZL is described with reference to  FIG. 26 . As shown in  FIG. 26 , this camera  1  has a lens assembly configuration including a replaceable imaging lens  2 . The zoom optical system having the configuration described above is provided in the imaging lens  2 . That is, the imaging lens  2  corresponds to the optical apparatus of the invention of the present application. The camera  1  is a digital camera. Light from an object (subject), not shown, is collected by the imaging lens  2 , and reaches an imaging element  3 . Accordingly, the light from the subject is imaged by the imaging element  3 , and recorded as a subject image in a memory, not shown. As described above, a photographer can take an image of the subject through the camera  1 . Note that this camera may be a mirrorless camera, or a single-lens reflex type camera including a quick return mirror. 
     According to the configuration described above, the camera  1  mounted with the zoom optical system ZL described above in the imaging lens  2  can achieve high-speed AF and silence during AF without increasing the size of the lens barrel by reducing the size and weight of the focusing lens group. Furthermore, variation of aberrations upon zooming from the wide-angle end state to the telephoto end state, and variation of aberrations upon focusing from an infinite distant object to a short distant object can be favorably suppressed, and a favorable optical performance can be achieved. 
     Subsequently, referring to  FIG. 27 , an overview of a method for manufacturing the aforementioned zoom optical system ZL is described. First, arrange, in order from an object, a front lens group GFS having a positive refractive power, an M1 lens group GM 1  having a negative refractive power, an M2 lens group GM 2  having a positive refractive power, and an RN lens group GRN having a negative refractive power (step ST 1 ). Then, achieve a configuration such that upon zooming, a distance between the front lens group GFS and the M1 lens group GM 1  changes, a distance between the M1 lens group GM 1  and the M2 lens group GM 2  changes, and a distance between the M2 lens group GM 2  and the RN lens group GRN changes (step ST 2 ). In this case, the RN lens group GRN is configured to move upon focusing from an infinite distant object to a short distant object (step ST 3 ), and lenses are arranged such that the M2 lens group GM 2  comprises the A lens group satisfying a predetermined conditional expression (step ST 4 ). 
     EXAMPLES 
     Hereinafter, zoom optical systems (zoom lens) ZL according to the examples of this embodiment are described with reference to the drawings.  FIGS. 1, 6, 11, 16 and 21  are sectional views showing the configurations and refractive power distributions of the zoom optical systems ZL {ZL ( 1 ) to ZL( 5 )} according to first to fifth examples. At lower parts of the sectional views of the zoom optical systems ZL( 1 ) to ZL( 5 ), the movement direction of each lens group along the optical axis during zooming from the wide-angle end state (W) to the telephoto end state (T) is indicated by a corresponding arrow. Furthermore, the movement direction during focusing the focusing group GRN from infinity to a short distant object is indicated by an arrow accompanied by characters “FOCUSING.” 
       FIGS. 1, 6, 11, 16 and 21  show each lens group by a combination of a symbol G and a numeral or alphabet (s), and show each lens by a combination of a symbol L and a numeral. In this case, to prevent the types and numbers of symbols and numerals from increasing and being complicated, the lens groups and the like are indicated using the combinations of symbols and numerals independently on an example-by-example basis. Accordingly, even though the same combinations of symbols and numerals are used among the examples, the combinations do not mean the same configurations. 
     Tables 1 to 5 are hereinafter shown below. Tables 1 to 5 are tables representing various data in the first to fifth examples. In each example, d-line (wavelength 587.562 nm) and g-line (wavelength 435.835 nm) are selected as calculation targets of aberration characteristics. 
     In [Lens data] tables, the surface number denotes the order of optical surfaces from the object along a light beam traveling direction, R denotes the radius of curvature (a surface whose center of curvature is nearer to the image is assumed to have a positive value) of each optical surface, D denotes the surface distance, which is the distance on the optical axis from each optical surface to the next optical surface (or the image surface), nd denotes the refractive index of the material of an optical element for the d-line, and νd denotes the Abbe number of the material of an optical element with reference to the d-line. The object surface denotes the surface of an object. “∞” of the radius of curvature indicates a flat surface or an aperture. (Stop S) indicates an aperture stop S. The image surface indicates an image surface I. The description of the air refractive index nd=1.00000 is omitted. 
     In [Various data] tables, f denotes the focal length of the entire zoom lens, FNO denotes the f-number, 2ω denotes the angle of view (represented in units of ° (degree); ω denotes the half angle of view), and Ymax denotes the maximum image height. TL denotes the distance obtained by adding BF to the distance on the optical axis from the lens forefront surface to the lens last surface upon focusing on infinity. BF denotes the distance (back focus) on the optical axis from the lens last surface to the image surface I upon focusing on infinity. Note that these values are represented for zooming states of the wide-angle end (W), the intermediate focal length (M), and the telephoto end (T). 
     [Variable distance data] tables show the surface distances at surface numbers (e.g., surface numbers 5, 13, 25 and 29 in First Example) to which the surface distance of “Variable” in the table representing [Lens data] correspond. This shows the surface distances in the zooming states of the wide-angle end (W), the intermediate focal length (M) and the telephoto end (T) upon focusing on infinity and a short distant object. 
     [Lens group data] tables show the starting surfaces (the surfaces nearest to the object) and the focal lengths of the first to fifth lens groups (or the first to fourth lens groups or the first to sixth lens groups). 
     [Conditional expression corresponding value] tables show values corresponding to the conditional expressions (1) to (9) described above. 
     Hereinafter, for all the data values, the listed focal length f, radius of curvature R, surface distance D, other lengths and the like are typically represented in “mm” if not otherwise specified. However, the optical system can exert equivalent optical performances even if being proportionally magnified or proportionally reduced. Consequently, the representation is not limited thereto. 
     The above descriptions of the tables are common to all the examples. Hereinafter, redundant description is omitted. 
     First Example 
     The first example is described with reference to  FIG. 1  and Table 1.  FIG. 1  shows a lens configuration of a zoom optical system according to the first example of this embodiment. The zoom optical system ZL( 1 ) according to this example consists of, in order from the object: a first lens group G 1  having a positive refractive power; a second lens group G 2  having a negative refractive power; a third lens group G 3  having a positive refractive power; a fourth lens group G 4  having a negative refractive power; and a fifth lens group G 5  having a positive refractive power. The sign (+) or (−) assigned to each lens group symbol indicates the refractive power of the corresponding lens group. This similarly applies to all the following examples. 
     In relation to the embodiment described above, in this configuration, the first lens group G 1  corresponds to the front lens group GFS, the second lens group G 2  corresponds to the M1 lens group GM 1 , the third lens group G 3  corresponds to the M2 lens group GM 2 , and the fourth lens group G 4  corresponds to the RN lens group GRN. 
     The first lens group G 1  consists of, in order from the object: a positive convexo-planar lens L 11  having a convex surface facing the object; and a positive cemented lens consisting of a negative meniscus lens L 12  having a convex surface facing the object, and a positive meniscus lens L 13  having a convex surface facing the object. 
     The second lens group G 2  consists of, in order from the object: a negative meniscus lens L 21  having a convex surface facing the object; a positive biconvex lens L 22 ; a negative biconcave lens L 23 ; and a negative meniscus lens L 24  having a concave surface facing the object. 
     The third lens group G 3  consists of, in order from the object: a positive cemented lens consisting of a negative meniscus lens L 31  having a convex surface facing the object, and a positive biconvex lens L 32 ; a positive cemented lens consisting of a positive biconvex lens L 33 , and a negative biconcave lens L 34 ; an aperture stop S; a negative cemented lens consisting of a negative meniscus lens L 35  having a convex surface facing the object, and a positive biconvex lens L 36 ; and a positive biconvex lens L 37 . 
     The fourth lens group G 4  consists of, in order from the object: a positive meniscus lens L 41  having a concave surface facing the object; and a negative biconcave lens L 42 . 
     The fifth lens group G 5  consists of, in order from the object: a negative meniscus lens L 51  having a concave surface facing the object; and a positive biconvex lens L 52 . 
     In the optical system according to this example, focusing from a long distant object to a short distant object is performed by moving the fourth lens group G 4  in the image surface direction. 
     The zoom optical system according to this example corrects the imaging position displacement due to a camera shake or the like by moving the positive cemented lens that consists of the negative meniscus lens L 31  having the convex surface facing the object and the positive biconvex lens L 32 , in a direction orthogonal to the optical axis. That is, the lenses L 31  and L 32  constitute the vibration-proof lens group, and correspond to the A lens group of the present invention and this embodiment. 
     To correct a rotational blur with an angle θ at a lens having the focal length f of the entire system and a vibration proof coefficient K (the ratio of the amount of image movement on the image forming surface to the amount of movement of the movable lens group upon blur correction), the movable lens group for blur correction may be moved in a direction orthogonal to the optical axis by (f·tan θ)/K. At the wide-angle end in the first example, the vibration proof coefficient is 1.65, and the focal length is 72.1 mm. Accordingly, the amount of movement of the vibration-proof lens group to correct a rotational blur by 0.30° is 0.23 mm. In the telephoto end state in the first example, the vibration proof coefficient is 2.10, and the focal length is 292.0 mm. Accordingly, the amount of movement of the vibration-proof lens group to correct a rotational blur by 0.20° is 0.49 mm. 
     The following Table 1 lists the values of data on the optical system according to this example. In Table 1, f denotes the focal length, and BF denotes the back focus. 
     
       
         
           
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 First Example 
               
               
                   
               
             
            
               
                 [Lens data] 
               
            
           
           
               
               
               
               
               
            
               
                 Surface No. 
                 R 
                 D 
                 nd 
                 νd 
               
               
                   
               
               
                 Object surface 
                 ∞ 
               
               
                 1 
                 109.4870 
                 4.600 
                 1.48749 
                 70.31 
               
               
                 2 
                 ∞ 
                 0.200 
               
               
                 3 
                 101.1800 
                 1.800 
                 1.62004 
                 36.40 
               
               
                 4 
                 49.8109 
                 7.200 
                 1.49700 
                 81.61 
               
               
                 5 
                 385.8166 
                 Variable 
               
               
                 6 
                 176.0187 
                 1.700 
                 1.69680 
                 55.52 
               
               
                 7 
                 31.3680 
                 5.150 
               
               
                 8 
                 32.6087 
                 5.500 
                 1.78472 
                 25.64 
               
               
                 9 
                 −129.7634 
                 1.447 
               
               
                 10 
                 −415.4105 
                 1.300 
                 1.77250 
                 49.62 
               
               
                 11 
                 34.3083 
                 4.300 
               
               
                 12 
                 −33.1502 
                 1.200 
                 1.85026 
                 32.35 
               
               
                 13 
                 −203.5644 
                 Variable 
               
               
                 14 
                 70.9040 
                 1.200 
                 1.80100 
                 34.92 
               
               
                 15 
                 30.2785 
                 5.900 
                 1.64000 
                 60.20 
               
               
                 16 
                 −70.1396 
                 1.500 
               
               
                 17 
                 34.0885 
                 6.000 
                 1.48749 
                 70.31 
               
               
                 18 
                 −42.6106 
                 1.300 
                 1.80610 
                 40.97 
               
               
                 19 
                 401.2557 
                 2.700 
               
               
                 20 
                 ∞ 
                 14.110  
                   
                 (Stop S) 
               
               
                 21 
                 350.0000 
                 1.200 
                 1.83400 
                 37.18 
               
               
                 22 
                 30.1592 
                 4.800 
                 1.51680 
                 63.88 
               
               
                 23 
                 −94.9908 
                 0.200 
               
               
                 24 
                 66.3243 
                 2.800 
                 1.80100 
                 34.92 
               
               
                 25 
                 −132.5118 
                 Variable 
               
               
                 26 
                 −92.0997 
                 2.200 
                 1.80518 
                 25.45 
               
               
                 27 
                 −44.0090 
                 6.500 
               
               
                 28 
                 −36.9702 
                 1.000 
                 1.77250 
                 49.62 
               
               
                 29 
                 68.3346 
                 Variable 
               
               
                 30 
                 −24.5000 
                 1.400 
                 1.62004 
                 36.40 
               
               
                 31 
                 −41.1519 
                 0.200 
               
               
                 32 
                 106.0000 
                 3.800 
                 1.67003 
                 47.14 
               
               
                 33 
                 −106.0000 
                 BF 
               
               
                 Image surface 
                 ∞ 
               
               
                   
               
            
           
           
               
            
               
                 [Various data] 
               
               
                 Zooming ratio 4.05 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 W 
                 M 
                 T 
               
               
                   
                   
               
               
                   
                 f 
                 72.1 
                 100.0 
                 292.0 
               
               
                   
                 FNO 
                 4.49 
                 4.86 
                 5.88 
               
               
                   
                 2ω 
                 33.96 
                 24.48 
                 8.44 
               
               
                   
                 Ymax 
                 21.60 
                 21.60 
                 21.60 
               
               
                   
                 TL 
                 190.13 
                 205.07 
                 245.82 
               
               
                   
                 BF 
                 39.12 
                 46.45 
                 67.12 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Variable distance data] 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                 W 
                 M 
                 T 
               
               
                   
                 W 
                 M 
                 T 
                 Short 
                 Short 
                 Short 
               
               
                   
                 Infinity 
                 Infinity 
                 Infinity 
                 distance 
                 distance 
                 distance 
               
               
                   
               
               
                 d5 
                 6.204 
                 21.150 
                 61.895 
                 6.204 
                 21.150 
                 61.895 
               
               
                 d13 
                 30.000 
                 22.666 
                 2.000 
                 30.000 
                 22.666 
                 2.000 
               
               
                 d25 
                 2.180 
                 3.742 
                 3.895 
                 2.837 
                 4.562 
                 5.614 
               
               
                 d29 
                 21.418 
                 19.856 
                 19.703 
                 20.761 
                 19.036 
                 17.984 
               
               
                   
               
            
           
           
               
            
               
                 [Lens group data] 
               
            
           
           
               
               
               
               
            
               
                   
                 Group 
                 Starting surface 
                 f 
               
               
                   
                   
               
               
                   
                 G1 
                 1 
                 145.319 
               
               
                   
                 G2 
                 6 
                 −29.546 
               
               
                   
                 G3 
                 14 
                 38.298 
               
               
                   
                 G4 
                 26 
                 −48.034 
               
               
                   
                 G5 
                 30 
                 324.470 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Conditional expression corresponding value] 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 (1) fvr/fTM2 = 1.755 
               
               
                   
                 (2) nvrN/nvrP = 1.098 
               
               
                   
                 (3) νvrN/νvrP = 0.580 
               
               
                   
                 (4) (−fTM1)/f1 = 0.203 
               
               
                   
                 (5) fTM2/f1 = 0.264 
               
               
                   
                 (6) (−fN)/fP = 1.266 
               
               
                   
                 (7) f1/fw = 2.016 
               
               
                   
                 (8) f1/(−fTM1) = 4.918 
               
               
                   
                 (9) f1/fTM2 = 3.794 
               
               
                   
                   
               
            
           
         
       
     
       FIGS. 2A and 2B  are graphs showing various aberrations of the zoom optical system having the vibration-proof function according to the first example upon focusing on infinity in the wide-angle end state, and graphs showing meridional lateral aberrations when blur correction is applied to a rotational blur by 0.30°, respectively.  FIG. 3  is graphs showing various aberrations of the zoom optical system having the vibration-proof function according to the first example upon focusing on infinity in the intermediate focal length state.  FIGS. 4A and 4B  are graphs showing various aberrations of the zoom optical system having the vibration-proof function according to the first example upon focusing on infinity in the telephoto end state, and graphs showing meridional lateral aberrations when blur correction is applied to a rotational blur by 0.20°, respectively.  FIGS. 5A, 5B and 5C  are graphs showing various aberrations of the zoom optical system according to the first example upon focusing on a short distant object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. 
     In the aberration graphs of  FIGS. 2 to 5 , FNO denotes the f-number, NA denotes the numerical aperture, and Y denotes the image height. Note that the spherical aberration graph shows the value of the f-number or the numerical aperture corresponding to the maximum aperture. The astigmatism graph and the distortion graph show the maximum value of the image height. The coma aberration graph shows the value of each image height. d denotes the d-line (λ=587.6 nm), and g denotes the g-line (λ=435.8 nm). In the astigmatism graph, solid lines indicate sagittal image surfaces, and broken lines indicate meridional image surfaces. Note that symbols analogous to those in this example are used also in the aberration graphs in the following examples. 
     The graphs showing various aberrations show that the zoom optical system according to this example favorably corrects the various aberrations and has excellent image forming performances from the wide-angle end state to the telephoto end state, and further has excellent image forming performances also upon focusing on a short distant object. 
     Second Example 
       FIG. 6  shows a lens configuration of a zoom optical system according to the second example of this embodiment. The zoom optical system according to this example consists of, in order from the object: a first lens group G 1  having a positive refractive power; a second lens group G 2  having a negative refractive power; a third lens group G 3  having a negative refractive power; a fourth lens group G 4  having a positive refractive power; a fifth lens group G 5  having a negative refractive power; and a sixth lens group G 6  having a positive refractive power. 
     In relation to the embodiment described above, in this configuration, the first lens group G 1  corresponds to the front lens group GFS, the second lens group G 2  and the third lens group G 3  correspond to the M1 lens group GM 1 , the fourth lens group G 4  corresponds to the M2 lens group GM 2 , and the fifth lens group G 5  corresponds to the RN lens group GRN. 
     The first lens group G 1  consists of, in order from the object: a positive convexo-planar lens L 11  having a convex surface facing the object; and a positive cemented lens consisting of a negative meniscus lens L 12  having a convex surface facing the object, and a positive meniscus lens L 13  having a convex surface facing the object. 
     The second lens group G 2  consists of, in order from the object: a negative meniscus lens L 21  having a convex surface facing the object; a positive biconvex lens L 22 ; and a negative biconcave lens L 23 . 
     The third lens group G 3  consists of a negative meniscus lens L 31  having a concave surface facing the object. 
     The fourth lens group G 4  consists of, in order from the object: a positive cemented lens consisting of a negative meniscus lens L 41  having a convex surface facing the object, and a positive biconvex lens L 42 ; a positive cemented lens consisting of a positive biconvex lens L 43 , and a negative biconcave lens L 44 ; an aperture stop S; a negative cemented lens consisting of a negative meniscus lens L 45  having a convex surface facing the object, and a positive biconvex lens L 46 ; and a positive biconvex lens L 47 . 
     The fifth lens group G 5  consists of, in order from the object: a positive meniscus lens L 51  having a concave surface facing the object; and a negative biconcave lens L 52 . 
     The sixth lens group G 6  consists of, in order from the object: a negative meniscus lens L 61  having a concave surface facing the object; and a positive biconvex lens L 62 . 
     In the optical system according to this example, focusing from a long distant object to a short distant object is performed by moving the fifth lens group G 5  in the image surface direction. The imaging position displacement due to a camera shake or the like is corrected by moving the positive cemented lens that consists of the negative meniscus lens L 41  having the convex surface facing the object and the positive biconvex lens L 42 , in a direction orthogonal to the optical axis. That is, the lenses L 41  and L 42  constitute the vibration-proof lens group, and correspond to the A lens group of the present invention and this embodiment. 
     Note that to correct a rotational blur with an angle θ at a lens having the focal length f of the entire system and a vibration proof coefficient K (the ratio of the amount of image movement on the image forming surface to the amount of movement of the movable lens group upon blur correction), the movable lens group for blur correction is moved in a direction orthogonal to the optical axis by (f·tan θ)/K. At the wide-angle end in the second example, the vibration proof coefficient is 1.66, and the focal length is 72.1 mm. Accordingly, the amount of movement of the vibration-proof lens group to correct a rotational blur by 0.30° is 0.23 mm. In the telephoto end state in the second example, the vibration proof coefficient is 2.10, and the focal length is 292.0 mm. Accordingly, the amount of movement of the vibration-proof lens group to correct a rotational blur by 0.20° is 0.49 mm. 
     The following Table 2 lists the values of data on the optical system according to this example. 
     
       
         
           
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Second Example 
               
               
                   
               
             
            
               
                 [Lens data] 
               
            
           
           
               
               
               
               
               
            
               
                 Surface No. 
                 R 
                 D 
                 nd 
                 νd 
               
               
                   
               
               
                 Object surface 
                 ∞ 
               
               
                 1 
                 107.5723 
                 4.600 
                 1.48749 
                 70.32 
               
               
                 2 
                 ∞ 
                 0.200 
               
               
                 3 
                 96.9007 
                 1.800 
                 1.62004 
                 36.40 
               
               
                 4 
                 47.8324 
                 7.200 
                 1.49700 
                 81.61 
               
               
                 5 
                 361.3792 
                 Variable 
               
               
                 6 
                 139.8663 
                 1.700 
                 1.69680 
                 55.52 
               
               
                 7 
                 33.7621 
                 6.806 
               
               
                 8 
                 33.5312 
                 5.500 
                 1.78472 
                 25.64 
               
               
                 9 
                 −139.8348 
                 0.637 
               
               
                 10 
                 −492.0620 
                 1.300 
                 1.80400 
                 46.60 
               
               
                 11 
                 35.1115 
                 Variable 
               
               
                 12 
                 −34.6163 
                 1.200 
                 1.83400 
                 37.18 
               
               
                 13 
                 −377.1306 
                 Variable 
               
               
                 14 
                 74.8969 
                 1.200 
                 1.80100 
                 34.92 
               
               
                 15 
                 31.6202 
                 5.900 
                 1.64000 
                 60.19 
               
               
                 16 
                 −69.0444 
                 1.500 
               
               
                 17 
                 34.2668 
                 6.000 
                 1.48749 
                 70.32 
               
               
                 18 
                 −42.8334 
                 1.300 
                 1.80610 
                 40.97 
               
               
                 19 
                 434.9585 
                 2.700 
               
               
                 20 
                 ∞ 
                 14.312  
                   
                 (Stop S) 
               
               
                 21 
                 350.0000 
                 1.200 
                 1.83400 
                 37.18 
               
               
                 22 
                 30.4007 
                 4.800 
                 1.51680 
                 63.88 
               
               
                 23 
                 −98.0361 
                 0.200 
               
               
                 24 
                 68.9306 
                 2.800 
                 1.80100 
                 34.92 
               
               
                 25 
                 −129.3404 
                 Variable 
               
               
                 26 
                 −90.5065 
                 2.200 
                 1.80518 
                 25.45 
               
               
                 27 
                 −44.1796 
                 6.500 
               
               
                 28 
                 −37.6907 
                 1.000 
                 1.77250 
                 49.62 
               
               
                 29 
                 68.3000 
                 Variable 
               
               
                 30 
                 −24.5545 
                 1.400 
                 1.62004 
                 36.40 
               
               
                 31 
                 −41.7070 
                 0.200 
               
               
                 32 
                 106.0000 
                 3.800 
                 1.67003 
                 47.14 
               
               
                 33 
                 −106.0000 
                 BF 
               
               
                 Image surface 
                 ∞ 
               
               
                   
               
            
           
           
               
            
               
                 [Various data] 
               
               
                 Zooming ratio 4.05 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 W 
                 M 
                 T 
               
               
                   
                   
               
               
                   
                 f 
                 72.1 
                 100.0 
                 292.0 
               
               
                   
                 FNO 
                 4.53 
                 4.89 
                 5.88 
               
               
                   
                 2ω 
                 33.98 
                 24.48 
                 8.44 
               
               
                   
                 Ymax 
                 21.60 
                 21.60 
                 21.60 
               
               
                   
                 TL 
                 190.82 
                 206.02 
                 245.82 
               
               
                   
                 BF 
                 39.12 
                 46.27 
                 66.46 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Variable distance data] 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                 W 
                 M 
                 T 
               
               
                   
                 W 
                 M 
                 T 
                 Short 
                 Short 
                 Short 
               
               
                   
                 Infinity 
                 Infinity 
                 Infinity 
                 distance 
                 distance 
                 distance 
               
               
                   
               
               
                 d5 
                 2.861 
                 18.057 
                 57.861 
                 2.861 
                 18.057 
                 57.861 
               
               
                 d11 
                 5.727 
                 5.812 
                 6.883 
                 5.727 
                 5.812 
                 6.883 
               
               
                 d13 
                 30.500 
                 23.259 
                 2.000 
                 30.500 
                 23.259 
                 2.000 
               
               
                 d25 
                 2.246 
                 3.634 
                 3.634 
                 2.888 
                 4.436 
                 5.329 
               
               
                 d29 
                 22.411 
                 21.023 
                 21.023 
                 21.770 
                 20.221 
                 19.329 
               
               
                   
               
            
           
           
               
            
               
                 [Lens group data] 
               
            
           
           
               
               
               
               
            
               
                   
                 Group 
                 Starting surface 
                 f 
               
               
                   
                   
               
               
                   
                 G1 
                 1 
                 141.867 
               
               
                   
                 G2 
                 6 
                 −104.910 
               
               
                   
                 G3 
                 12 
                 −45.774 
               
               
                   
                 G4 
                 14 
                 38.681 
               
               
                   
                 G5 
                 26 
                 −48.266 
               
               
                   
                 G6 
                 30 
                 340.779 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Conditional expression corresponding value] 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 (1) fvr/fIM2 = 1.764 
               
               
                   
                 (2) nvrN/nvrP = 1.098 
               
               
                   
                 (3) νvrN/νvrP = 0.580 
               
               
                   
                 (4) (−fTM1)/f1 = 0.208 
               
               
                   
                 (5) fTM2/f1 = 0.273 
               
               
                   
                 (6) (−fN)/fP = 1.248 
               
               
                   
                 (7) f1/fw = 1.968 
               
               
                   
                 (8) f1/(−fTM1) = 4.804 
               
               
                   
                 (9) f1/fTM2 = 3.668 
               
               
                   
                   
               
            
           
         
       
     
       FIGS. 7A and 7B  are graphs showing various aberrations of the zoom optical system having the vibration-proof function according to the second example upon focusing on infinity in the wide-angle end state, and graphs showing meridional lateral aberrations when blur correction is applied to a rotational blur by 0.30°, respectively.  FIG. 8  is graphs showing various aberrations of the zoom optical system having the vibration-proof function according to the second example upon focusing on infinity in the intermediate focal length state.  FIGS. 9A and 9B  are graphs showing various aberrations of the zoom optical system having the vibration-proof function according to the second example upon focusing on infinity in the telephoto end state, and graphs showing meridional lateral aberrations when blur correction is applied to a rotational blur by 0.20°, respectively.  FIGS. 10A, 10B and 10C  are graphs showing various aberrations of the zoom optical system according to the second example upon focusing on a short distant object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. 
     The graphs showing various aberrations show that the zoom optical system according to this example favorably corrects the various aberrations and has excellent image forming performances from the wide-angle end state to the telephoto end state, and further has excellent image forming performances also upon focusing on a short distant object. 
     Third Example 
       FIG. 11  shows a lens configuration of a zoom optical system according to the third example of this embodiment. The zoom optical system according to this example consists of, in order from the object: a first lens group G 1  having a positive refractive power; a second lens group G 2  having a negative refractive power; a third lens group G 3  having a positive refractive power; a fourth lens group G 4  having a positive refractive power; a fifth lens group G 5  having a negative refractive power; and a sixth lens group having a positive refractive power. 
     In relation to the embodiment described above, in this configuration, the first lens group G 1  corresponds to the front lens group GFS, the second lens group G 2  corresponds to the M1 lens group GM 1 , the third lens group G 3  and the fourth lens group G 4  correspond to the M2 lens group GM 2 , and the fifth lens group G 5  corresponds to the RN lens group GRN. 
     The first lens group G 1  consists of, in order from the object: a positive convexo-planar lens L 11  having a convex surface facing the object; and a positive cemented lens consisting of a negative meniscus lens L 12  having a convex surface facing the object, and a positive meniscus lens L 13  having a convex surface facing the object. 
     The second lens group G 2  consists of, in order from the object: a negative meniscus lens L 21  having a convex surface facing the object; a positive biconvex lens L 22 ; a negative biconcave lens L 23 ; and a negative meniscus lens L 24  having a concave surface facing the object. 
     The third lens group G 3  consists of, in order from the object: a positive cemented lens consisting of a negative meniscus lens L 31  having a convex surface facing the object, and a positive biconvex lens L 32 ; a positive cemented lens consisting of a positive biconvex lens L 33 , and a negative biconcave lens L 34 ; and an aperture stop S. 
     The fourth lens group G 4  consists of, in order from the object: a negative cemented lens consisting of a negative meniscus lens L 41  having a convex surface facing the object, and a positive biconvex lens L 42 ; and a positive biconvex lens L 43 . 
     The fifth lens group G 5  consists of, in order from the object: a positive meniscus lens L 51  having a concave surface facing the object; and a negative biconcave lens L 52 . 
     The sixth lens group G 6  consists of, in order from the object: a negative meniscus lens L 61  having a concave surface facing the object; and a positive biconvex lens L 62 . 
     In the optical system according to this example, focusing from a long distant object to a short distant object is performed by moving the fifth lens group G 5  in the image surface direction. The imaging position displacement due to a camera shake or the like is corrected by moving the positive cemented lens that consists of the negative meniscus lens L 31  having the convex surface facing the object and the positive biconvex lens L 32 , in a direction orthogonal to the optical axis. That is, the lenses L 31  and L 32  constitute the vibration-proof lens group, and correspond to the A lens group of the present invention and this embodiment. 
     Note that to correct a rotational blur with an angle θ at a lens having the focal length f of the entire system and a vibration proof coefficient K (the ratio of the amount of image movement on the image forming surface to the amount of movement of the movable lens group upon blur correction), the movable lens group for blur correction is moved in a direction orthogonal to the optical axis by (f·tan θ)/K. At the wide-angle end in the third example, the vibration proof coefficient is 1.65, and the focal length is 72.1 mm. Accordingly, the amount of movement of the vibration-proof lens group to correct a rotational blur by 0.30° is 0.23 mm. In the telephoto end state in the third example, the vibration proof coefficient is 2.10, and the focal length is 292.0 mm. Accordingly, the amount of movement of the vibration-proof lens group to correct a rotational blur by 0.20° is 0.49 mm. 
     The following Table 3 lists the values of data on the optical system according to this example. 
     
       
         
           
               
             
               
                 TABLE 3 
               
               
                   
               
               
                 Third Example 
               
               
                   
               
             
            
               
                 [Lens data] 
               
            
           
           
               
               
               
               
               
            
               
                 Surface No. 
                 R 
                 D 
                 nd 
                 νd 
               
               
                   
               
               
                 Object surface 
                 ∞ 
               
               
                 1 
                 106.7563 
                 4.600 
                 1.48749 
                 70.32 
               
               
                 2 
                 ∞ 
                 0.200 
               
               
                 3 
                 99.4635 
                 1.800 
                 1.62004 
                 36.40 
               
               
                 4 
                 49.2336 
                 7.200 
                 1.49700 
                 81.61 
               
               
                 5 
                 332.7367 
                 Variable 
               
               
                 6 
                 152.3830 
                 1.700 
                 1.69680 
                 55.52 
               
               
                 7 
                 31.0229 
                 5.695 
               
               
                 8 
                 32.0867 
                 5.500 
                 1.78472 
                 25.64 
               
               
                 9 
                 −139.5695 
                 1.399 
               
               
                 10 
                 −403.4713 
                 1.300 
                 1.77250 
                 49.62 
               
               
                 11 
                 33.8214 
                 4.300 
               
               
                 12 
                 −34.0003 
                 1.200 
                 1.85026 
                 32.35 
               
               
                 13 
                 −235.0206 
                 Variable 
               
               
                 14 
                 69.3622 
                 1.200 
                 1.80100 
                 34.92 
               
               
                 15 
                 29.8420 
                 5.900 
                 1.64000 
                 60.19 
               
               
                 16 
                 −71.2277 
                 1.500 
               
               
                 17 
                 34.4997 
                 6.000 
                 1.48749 
                 70.32 
               
               
                 18 
                 −43.1246 
                 1.300 
                 1.80610 
                 40.97 
               
               
                 19 
                 382.2412 
                 2.700 
               
               
                 20 
                 ∞ 
                 Variable 
                   
                 (Stop S) 
               
               
                 21 
                 350.0000 
                 1.200 
                 1.83400 
                 37.18 
               
               
                 22 
                 30.6178 
                 4.800 
                 1.51680 
                 63.88 
               
               
                 23 
                 −88.2508 
                 0.200 
               
               
                 24 
                 66.4312 
                 2.800 
                 1.80100 
                 34.92 
               
               
                 25 
                 −142.7832 
                 Variable 
               
               
                 26 
                 −93.6206 
                 2.200 
                 1.80518 
                 25.45 
               
               
                 27 
                 −44.3477 
                 6.500 
               
               
                 28 
                 −37.1859 
                 1.000 
                 1.77250 
                 49.62 
               
               
                 29 
                 68.3000 
                 Variable 
               
               
                 30 
                 −24.9508 
                 1.400 
                 1.62004 
                 36.40 
               
               
                 31 
                 −42.7086 
                 0.200 
               
               
                 32 
                 106.0000 
                 3.800 
                 1.67003 
                 47.14 
               
               
                 33 
                 −106.0000 
                 BF 
               
               
                 Image surface 
                 ∞ 
               
               
                   
               
            
           
           
               
            
               
                 [Various data] 
               
               
                 Zooming ratio 4.05 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 W 
                 M 
                 T 
               
               
                   
                   
               
               
                   
                 f 
                 72.1 
                 100.0 
                 292.0 
               
               
                   
                 FNO 
                 4.49 
                 4.85 
                 5.88 
               
               
                   
                 2ω 
                 33.98 
                 24.48 
                 8.44 
               
               
                   
                 Ymax 
                 21.60 
                 21.60 
                 21.60 
               
               
                   
                 TL 
                 190.26 
                 205.79 
                 245.82 
               
               
                   
                 BF 
                 39.12 
                 46.10 
                 67.12 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Variable distance data] 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                 W 
                 M 
                 T 
               
               
                   
                 W 
                 M 
                 T 
                 Short 
                 Short 
                 Short 
               
               
                   
                 Infinity 
                 Infinity 
                 Infinity 
                 distance 
                 distance 
                 distance 
               
               
                   
               
               
                 d5 
                 5.981 
                 21.510 
                 61.535 
                 5.981 
                 21.510 
                 61.535 
               
               
                 d13 
                 30.000 
                 23.014 
                 2.000 
                 30.000 
                 23.014 
                 2.000 
               
               
                 d20 
                 14.365 
                 14.107 
                 14.196 
                 14.365 
                 14.107 
                 14.196 
               
               
                 d25 
                 2.202 
                 3.476 
                 3.676 
                 2.867 
                 4.301 
                 5.396 
               
               
                 d29 
                 21.004 
                 19.988 
                 19.700 
                 20.339 
                 19.163 
                 17.979 
               
               
                   
               
            
           
           
               
            
               
                 [Lens group data] 
               
            
           
           
               
               
               
               
            
               
                   
                 Group 
                 Starting surface 
                 f 
               
               
                   
                   
               
               
                   
                 G1 
                 1 
                 145.335 
               
               
                   
                 G2 
                 6 
                 −29.607 
               
               
                   
                 G3 
                 14 
                 48.974 
               
               
                   
                 G4 
                 21 
                 62.364 
               
               
                   
                 G5 
                 26 
                 −48.296 
               
               
                   
                 G6 
                 30 
                 336.791 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Conditional expression corresponding value] 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 (1) fvr/f1M2 = 1.747 
               
               
                   
                 (2) nvrN/nvrP = 1.098 
               
               
                   
                 (3) νvrN/νvrP = 0.580 
               
               
                   
                 (4) (−fTM1)/f1 = 0.204 
               
               
                   
                 (5) fTM2/f1 = 0.264 
               
               
                   
                 (6) (−fN)/fP = 1.253 
               
               
                   
                 (7) f1/fw = 2.016 
               
               
                   
                 (8) f1/(−fTM1) = 4.909 
               
               
                   
                 (9) f1/fTM2 = 3.786 
               
               
                   
                   
               
            
           
         
       
     
       FIGS. 12A and 12B  are graphs showing various aberrations of the zoom optical system having a vibration-proof function according to the third example upon focusing on infinity in the wide-angle end state, and graphs showing meridional lateral aberrations when blur correction is applied to a rotational blur by 0.30°, respectively.  FIG. 13  is graphs showing various aberrations of the zoom optical system having the vibration-proof function according to the third example upon focusing on infinity in the intermediate focal length state.  FIGS. 14A and 14B  are graphs showing various aberrations of the zoom optical system having a vibration-proof function according to the third example upon focusing on infinity in the telephoto end state, and graphs showing meridional lateral aberrations when blur correction is applied to a rotational blur by 0.20°, respectively.  FIGS. 15A, 15B and 15C  are graphs showing various aberrations of the zoom optical system according to the third example upon focusing on a short distant object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. 
     The graphs showing various aberrations show that the zoom optical system according to this example favorably corrects the various aberrations and has excellent image forming performances from the wide-angle end state to the telephoto end state, and further has excellent image forming performances also upon focusing on a short distant object. 
     Fourth Example 
       FIG. 16  shows a lens configuration of a zoom optical system according to the fourth example of this embodiment. The zoom optical system according to this example consists of, in order from the object: a first lens group G 1  having a positive refractive power; a second lens group G 2  having a negative refractive power; a third lens group G 3  having a positive refractive power; and a fourth lens group G 4  having a negative refractive power. 
     In relation to the embodiment described above, in this configuration, the first lens group G 1  corresponds to the front lens group GFS, the second lens group G 2  corresponds to the M1 lens group GM 1 , the third lens group G 3  corresponds to the M2 lens group GM 2 , and the fourth lens group G 4  corresponds to the RN lens group GRN. 
     The first lens group G 1  consists of, in order from the object: a positive convexo-planar lens L 11  having a convex surface facing the object; and a positive cemented lens consisting of a negative meniscus lens L 12  having a convex surface facing the object, and a positive biconvex lens L 13 . 
     The second lens group G 2  consists of, in order from the object: a negative meniscus lens L 21  having a convex surface facing the object; a positive biconvex lens L 22 ; a negative biconcave lens L 23 ; and a negative meniscus lens L 24  having a concave surface facing the object. 
     The third lens group G 3  consists of, in order from the object: a positive cemented lens consisting of a negative meniscus lens L 31  having a convex surface facing the object, and a positive biconvex lens L 32 ; a positive cemented lens consisting of a positive biconvex lens L 33 , and a negative meniscus lens L 34  having a concave surface facing the object; an aperture stop S; a negative cemented lens consisting of a negative meniscus lens L 35  having a convex surface facing the object, and a positive biconvex lens L 36 ; and a positive biconvex lens L 37 . 
     The fourth lens group G 4  consists of, in order from the object: a positive meniscus lens L 41  having a concave surface facing the object; and a negative biconcave lens L 42 . 
     In the optical system according to this example, focusing from a long distant object to a short distant object is performed by moving the fourth lens group G 4  in the image surface direction. 
     The zoom optical system according to this example corrects the imaging position displacement due to a camera shake or the like by moving the positive cemented lens consisting of the negative meniscus lens L 31  having the convex surface facing the object and the positive biconvex lens L 32 , in a direction orthogonal to the optical axis. That is, the lenses L 31  and L 32  constitute the vibration-proof lens group, and correspond to the A lens group of the present invention and this embodiment. 
     Note that to correct a rotational blur with an angle θ at a lens having the focal length f of the entire system and a vibration proof coefficient K (the ratio of the amount of image movement on the image forming surface to the amount of movement of the movable lens group upon blur correction), the movable lens group for blur correction may be moved in a direction orthogonal to the optical axis by (f·tan θ)/K. At the wide-angle end in the fourth example, the vibration proof coefficient is 1.64, and the focal length is 72.1 mm. Accordingly, the amount of movement of the vibration-proof lens group to correct a rotational blur by 0.30° is 0.23 mm. In the telephoto end state in the fourth example, the vibration proof coefficient is 2.10, and the focal length is 292.0 mm. Accordingly, the amount of movement of the vibration-proof lens group to correct a rotational blur by 0.20° is 0.48 mm. 
     The following Table 4 lists the values of data on the optical system according to this example. 
     
       
         
           
               
             
               
                 TABLE 4 
               
               
                   
               
               
                 Fourth Example 
               
               
                   
               
             
            
               
                 [Lens data] 
               
            
           
           
               
               
               
               
               
            
               
                 Surface No. 
                 R 
                 D 
                 nd 
                 νd 
               
               
                   
               
               
                 Object surface 
                 ∞ 
               
               
                 1 
                 124.8083 
                 4.600 
                 1.48749 
                 70.32 
               
               
                 2 
                 ∞ 
                 0.200 
               
               
                 3 
                 111.5077 
                 1.800 
                 1.62004 
                 36.40 
               
               
                 4 
                 51.2894 
                 7.200 
                 1.49700 
                 81.61 
               
               
                 5 
                 −4057.4569 
                 Variable 
               
               
                 6 
                 1232.8716 
                 1.700 
                 1.69680 
                 55.52 
               
               
                 7 
                 32.6209 
                 3.624 
               
               
                 8 
                 33.1180 
                 5.224 
                 1.78472 
                 25.64 
               
               
                 9 
                 −126.9611 
                 1.768 
               
               
                 10 
                 −243.6400 
                 1.300 
                 1.77250 
                 49.62 
               
               
                 11 
                 37.7537 
                 4.300 
               
               
                 12 
                 −33.1285 
                 1.200 
                 1.85026 
                 32.35 
               
               
                 13 
                 −124.4232 
                 Variable 
               
               
                 14 
                 80.2408 
                 1.200 
                 1.80100 
                 34.92 
               
               
                 15 
                 32.8582 
                 5.862 
                 1.64000 
                 60.19 
               
               
                 16 
                 −70.9140 
                 1.500 
               
               
                 17 
                 40.5722 
                 6.000 
                 1.48749 
                 70.32 
               
               
                 18 
                 −43.0594 
                 1.300 
                 1.80610 
                 40.97 
               
               
                 19 
                 −2388.6437 
                 2.700 
               
               
                 20 
                 ∞ 
                 18.922  
                   
                 (Stop S) 
               
               
                 21 
                 812.4602 
                 1.200 
                 1.83400 
                 37.18 
               
               
                 22 
                 34.5376 
                 5.275 
                 1.51680 
                 63.88 
               
               
                 23 
                 −59.1982 
                 0.200 
               
               
                 24 
                 75.5608 
                 3.209 
                 1.80100 
                 34.92 
               
               
                 25 
                 −197.1038 
                 Variable 
               
               
                 26 
                 −76.9453 
                 2.263 
                 1.80518 
                 25.45 
               
               
                 27 
                 −41.7537 
                 6.500 
               
               
                 28 
                 −33.9973 
                 1.000 
                 1.77250 
                 49.62 
               
               
                 29 
                 132.3165 
                 BF 
               
               
                 Image surface 
                 ∞ 
               
               
                   
               
            
           
           
               
            
               
                 [Various data] 
               
               
                 Zooming ratio 4.05 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 W 
                 M 
                 T 
               
               
                   
                   
               
               
                   
                 f 
                 72.1 
                 100.0 
                 292.0 
               
               
                   
                 FNO 
                 4.68 
                 4.90 
                 6.19 
               
               
                   
                 2ω 
                 33.78 
                 23.92 
                 8.22 
               
               
                   
                 Ymax 
                 21.60 
                 21.60 
                 21.60 
               
               
                   
                 TL 
                 189.82 
                 210.78 
                 245.82 
               
               
                   
                 BF 
                 64.99 
                 69.56 
                 89.99 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Variable distance data] 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                 W 
                 M 
                 T 
               
               
                   
                 W 
                 M 
                 T 
                 Short 
                 Short 
                 Short 
               
               
                   
                 Infinity 
                 Infinity 
                 Infinity 
                 distance 
                 distance 
                 distance 
               
               
                   
               
               
                 d5 
                 2.000 
                 22.956 
                 58.000 
                 2.000 
                 22.956 
                 58.000 
               
               
                 d13 
                 30.000 
                 25.721 
                 2.000 
                 30.000 
                 25.721 
                 2.000 
               
               
                 d25 
                 2.777 
                 2.495 
                 5.785 
                 3.449 
                 3.343 
                 7.497 
               
               
                   
               
            
           
           
               
            
               
                 [Lens group data] 
               
            
           
           
               
               
               
               
            
               
                   
                 Group 
                 Starting surface 
                 f 
               
               
                   
                   
               
               
                   
                 G1 
                 1 
                 139.523 
               
               
                   
                 G2 
                 6 
                 −29.733 
               
               
                   
                 G3 
                 14 
                 41.597 
               
               
                   
                 G4 
                 26 
                 −54.885 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Conditional expression corresponding value] 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 (1) fvr/fTM2 = 1.728 
               
               
                   
                 (2) nvrN/nvrP = 1.098 
               
               
                   
                 (3) νvrN/νvrP = 0.580 
               
               
                   
                 (4) (−fTM1)/f1 = 0.213 
               
               
                   
                 (5) fTM2/f1 = 0.298 
               
               
                   
                 (7) f1/fw = 1.935 
               
               
                   
                 (8) f1/(−fTM1) = 4.693 
               
               
                   
                 (9) f1/fTM2 = 3.354 
               
               
                   
                   
               
            
           
         
       
     
       FIGS. 17A and 17B  are graphs showing various aberrations of the zoom optical system having the vibration-proof function according to the fourth example upon focusing on infinity in the wide-angle end state, and graphs showing meridional lateral aberrations when blur correction is applied to a rotational blur by 0.30°, respectively.  FIG. 18  is graphs showing various aberrations of the zoom optical system having the vibration-proof function according to the fourth example upon focusing on infinity in the intermediate focal length state.  FIGS. 19A and 19B  are graphs showing various aberrations of the zoom optical system having the vibration-proof function according to the fourth example upon focusing on infinity in the telephoto end state, and graphs showing meridional lateral aberrations when blur correction is applied to a rotational blur by 0.20°, respectively.  FIGS. 20A, 20B and 20C  are graphs showing various aberrations of the zoom optical system according to the fourth example upon focusing on a short distant object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. 
     The graphs showing various aberrations show that the zoom optical system according to this example favorably corrects the various aberrations and has excellent image forming performances from the wide-angle end state to the telephoto end state, and further has excellent image forming performances also upon focusing on a short distant object. 
     Fifth Example 
       FIG. 21  shows a lens configuration of a zoom optical system according to the fifth example of this embodiment. The zoom optical system according to this example consists of, in order from the object: a first lens group G 1  having a positive refractive power; a second lens group G 2  having a negative refractive power; a third lens group G 3  having a positive refractive power; a fourth lens group G 4  having a negative refractive power; and a fifth lens group G 5  having a positive refractive power. 
     In relation to the embodiment described above, in this configuration, the first lens group G 1  corresponds to the front lens group GFS, the second lens group G 2  corresponds to the M1 lens group GM 1 , the third lens group G 3  corresponds to the M2 lens group GM 2 , and the fourth lens group G 4  corresponds to the RN lens group GRN. 
     The first lens group G 1  consists of, in order from the object: a positive convexo-planar lens L 11  having a convex surface facing the object; and a positive cemented lens consisting of a negative meniscus lens L 12  having a convex surface facing the object, and a positive meniscus lens L 13  having a convex surface facing the object. 
     The second lens group G 2  consists of, in order from the object: a negative meniscus lens L 21  having a convex surface facing the object; a positive biconvex lens L 22 ; a negative biconcave lens L 23 ; and a negative meniscus lens L 24  having a concave surface facing the object. 
     The third lens group G 3  consists of, in order from the object: a positive cemented lens consisting of a negative meniscus lens L 31  having a convex surface facing the object, and a positive biconvex lens L 32 ; a positive cemented lens consisting of a positive biconvex lens L 33 , and a negative biconcave lens L 34 ; an aperture stop S; a negative cemented lens consisting of a negative meniscus lens L 35  having a convex surface facing the object, and a positive biconvex lens L 36 ; and a positive biconvex lens L 37 . 
     The fourth lens group G 4  consists of, in order from the object: a positive meniscus lens L 41  having a concave surface facing the object; and a negative biconcave lens L 42 . 
     The fifth lens group G 5  consists of, in order from the object: a negative meniscus lens L 51  having a concave surface facing the object; a positive biconvex lens L 52 ; and a positive meniscus lens L 53  having a convex surface facing the object. 
     In the optical system according to this example, focusing from a long distant object to a short distant object is performed by moving the fourth lens group G 4  in the image surface direction. The imaging position displacement due to a camera shake or the like is corrected by moving the positive cemented lens that consists of the negative meniscus lens L 31  having the convex surface facing the object and the positive biconvex lens L 32 , in a direction orthogonal to the optical axis. That is, the lenses L 31  and L 32  constitute the vibration-proof lens group, and correspond to the A lens group of the present invention and this embodiment. 
     Note that to correct a rotational blur with an angle θ at a lens having the focal length f of the entire system and a vibration proof coefficient K (the ratio of the amount of image movement on the image forming surface to the amount of movement of the movable lens group upon blur correction), the movable lens group for blur correction is moved in a direction orthogonal to the optical axis by (f·tan θ)/K. At the wide-angle end in the fourth example, the vibration proof coefficient is 1.65, and the focal length is 72.1 mm. Accordingly, the amount of movement of the vibration-proof lens group to correct a rotational blur by 0.30° is 0.23 mm. In the telephoto end state in the fourth example, the vibration proof coefficient is 2.10, and the focal length is 292.0 mm. Accordingly, the amount of movement of the vibration-proof lens group to correct a rotational blur by 0.20° is 0.49 mm. 
     The following Table 5 lists the values of data on the optical system according to this example. 
     
       
         
           
               
             
               
                 TABLE 5 
               
               
                   
               
               
                 Fifth Example 
               
               
                   
               
             
            
               
                 [Lens data] 
               
            
           
           
               
               
               
               
               
            
               
                 Surface No. 
                 R 
                 D 
                 nd 
                 νd 
               
               
                   
               
               
                 Object surface 
                 ∞ 
               
               
                 1 
                 109.5099 
                 4.600 
                 1.48749 
                 70.32 
               
               
                 2 
                 ∞ 
                 0.200 
               
               
                 3 
                 101.8486 
                 1.800 
                 1.62004 
                 36.40 
               
               
                 4 
                 49.8873 
                 7.200 
                 1.49700 
                 81.61 
               
               
                 5 
                 403.0130 
                 Variable 
               
               
                 6 
                 166.1577 
                 1.700 
                 1.69680 
                 55.52 
               
               
                 7 
                 31.1882 
                 3.953 
               
               
                 8 
                 32.0256 
                 5.500 
                 1.78472 
                 25.64 
               
               
                 9 
                 −139.5816 
                 1.553 
               
               
                 10 
                 −767.2482 
                 1.300 
                 1.77250 
                 49.62 
               
               
                 11 
                 33.9202 
                 4.300 
               
               
                 12 
                 −32.8351 
                 1.200 
                 1.85026 
                 32.35 
               
               
                 13 
                 −256.2484 
                 Variable 
               
               
                 14 
                 69.5902 
                 1.200 
                 1.80100 
                 34.92 
               
               
                 15 
                 29.9877 
                 5.900 
                 1.64000 
                 60.19 
               
               
                 16 
                 −70.0411 
                 1.500 
               
               
                 17 
                 36.2271 
                 6.000 
                 1.48749 
                 70.32 
               
               
                 18 
                 −39.9358 
                 1.300 
                 1.80610 
                 40.97 
               
               
                 19 
                 820.8027 
                 2.700 
               
               
                 20 
                 ∞ 
                 14.092  
                   
                 (Stop S) 
               
               
                 21 
                 427.1813 
                 1.200 
                 1.83400 
                 37.18 
               
               
                 22 
                 31.7606 
                 4.800 
                 1.51680 
                 63.88 
               
               
                 23 
                 −89.4727 
                 0.200 
               
               
                 24 
                 73.5865 
                 2.800 
                 1.80100 
                 34.92 
               
               
                 25 
                 −110.0493 
                 Variable 
               
               
                 26 
                 −83.7398 
                 2.200 
                 1.80518 
                 25.45 
               
               
                 27 
                 −42.9999 
                 6.500 
               
               
                 28 
                 −36.8594 
                 1.000 
                 1.77250 
                 49.62 
               
               
                 29 
                 73.0622 
                 Variable 
               
               
                 30 
                 −26.0662 
                 1.400 
                 1.62004 
                 36.4 
               
               
                 31 
                 −40.4068 
                 0.200 
               
               
                 32 
                 143.0444 
                 3.035 
                 1.67003 
                 47.14 
               
               
                 33 
                 −220.8402 
                 0.200 
               
               
                 34 
                 100.4330 
                 2.145 
                 1.79002 
                 47.32 
               
               
                 35 
                 170.3325 
                 BF 
               
               
                 Image surface 
                 ∞ 
               
               
                   
               
            
           
           
               
            
               
                 [Various data] 
               
               
                 Zooming ratio 4.05 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 W 
                 M 
                 T 
               
               
                   
                   
               
               
                   
                 f 
                 72.1 
                 100.0 
                 292.0 
               
               
                   
                 FNO 
                 4.48 
                 4.85 
                 5.87 
               
               
                   
                 2ω 
                 33.94 
                 24.44 
                 8.42 
               
               
                   
                 Ymax 
                 21.60 
                 21.60 
                 21.60 
               
               
                   
                 TL 
                 190.21 
                 205.27 
                 245.82 
               
               
                   
                 BF 
                 39.12 
                 46.37 
                 67.13 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Variable distance data] 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                 W 
                 M 
                 T 
               
               
                   
                 W 
                 M 
                 T 
                 Short 
                 Short 
                 Short 
               
               
                   
                 Infinity 
                 Infinity 
                 Infinity 
                 distance 
                 distance 
                 distance 
               
               
                   
               
               
                 d5 
                 5.892 
                 20.953 
                 61.502 
                 5.892 
                 20.953 
                 61.502 
               
               
                 d13 
                 30.000 
                 22.752 
                 2.000 
                 30.000 
                 22.752 
                 2.000 
               
               
                 d25 
                 2.212 
                 3.707 
                 3.900 
                 2.864 
                 4.521 
                 5.606 
               
               
                 d29 
                 21.306 
                 19.811 
                 19.618 
                 20.654 
                 18.997 
                 17.912 
               
               
                   
               
            
           
           
               
            
               
                 [Lens group data] 
               
            
           
           
               
               
               
               
            
               
                   
                 Group 
                 Starting surface 
                 f 
               
               
                   
                   
               
               
                   
                 G1 
                 1 
                 145.022 
               
               
                   
                 G2 
                 6 
                 −29.562 
               
               
                   
                 G3 
                 14 
                 38.233 
               
               
                   
                 G4 
                 26 
                 −48.257 
               
               
                   
                 G5 
                 30 
                 318.066 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Conditional expression corresponding value] 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 (1) fvr/fTM2 = 1.738 
               
               
                   
                 (2) nvrN/nvrP = 1.098 
               
               
                   
                 (3) νvrN/νvrP = 0.580 
               
               
                   
                 (4) (−fTM1)/f1 = 0.204 
               
               
                   
                 (5) fTM2/f1 = 0.264 
               
               
                   
                 (6) (−fN)/fP = 0.947 
               
               
                   
                 (7) f1/fw = 2.011 
               
               
                   
                 (8) f1/(−fTM1) = 4.906 
               
               
                   
                 (9) f1/fTM2 = 3.793 
               
               
                   
                   
               
            
           
         
       
     
       FIGS. 22A and 22B  are graphs showing various aberrations of the zoom optical system having a vibration-proof function according to the fifth example upon focusing on infinity in the wide-angle end state, and graphs showing meridional lateral aberrations when blur correction is applied to a rotational blur by 0.30°, respectively.  FIG. 23  is graphs showing various aberrations of the zoom optical system having the vibration-proof function according to the fifth example upon focusing on infinity in the intermediate focal length state.  FIGS. 24A and 24B  are graphs showing various aberrations of the zoom optical system having a vibration-proof function according to the fifth example upon focusing on infinity in the telephoto end state, and graphs showing meridional lateral aberrations when blur correction is applied to a rotational blur by 0.20°, respectively.  FIGS. 25A, 25B and 25C  are graphs showing various aberrations of the zoom optical system according to the fifth example upon focusing on a short distant object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. 
     The graphs showing various aberrations show that the zoom optical system according to this example favorably corrects the various aberrations and has excellent image forming performances from the wide-angle end state to the telephoto end state, and further has excellent image forming performances also upon focusing on a short distant object. 
     According to each of the examples described above, reduction in size and weight of the focusing lens group can achieve high-speed AF and silence during AF without increasing the size of the lens barrel, and the zoom optical system can be achieved that favorably suppresses variation of aberrations upon zooming from the wide-angle end state to the telephoto end state, and variation of aberrations upon focusing from an infinite distant object to a short distant object. 
     Here, each of the examples described above represents a specific example of the invention of the present application. The invention of the present application is not limited thereto. 
     Note that the following details can be appropriately adopted in a range without impairing the optical performance of the zoom optical system of the present application. 
     The five-group configurations and the six-group configurations have been described as the numeric examples of the zoom optical systems of the present application. However, the present application is not limited thereto. Zoom optical systems having other group configurations (for example, seven-group ones and the like) can also be configured. Specifically, a zoom optical system having a configuration where a lens or a lens group is added to the zoom optical system of the present application at a position nearest to the object or to the image surface may be configured. Note that the lens group indicates a portion that has at least one lens and is separated by air distances varying upon zooming. 
     The lens surfaces of the lenses constituting the zoom optical system of the present application may be spherical surfaces, plane surfaces, or aspherical surfaces. A case where the lens surface is a spherical surface or a plane surface facilitates lens processing and assembly adjustment, and can prevent the optical performance from being reduced owing to the errors in lens processing or assembly adjustment. Consequently, the case is preferable. It is also preferable because reduction in depiction performance is small even when the image surface deviates. In a case where the lens surface is an aspherical surface, the surface may be an aspherical surface made by a grinding process, a glass mold aspherical surface made by forming glass into an aspherical shape with a mold, or a composite type aspherical surface made by forming resin provided on the glass surface into an aspherical shape. The lens surface may be a diffractive surface. The lens may be a gradient index lens (GRIN lens) or a plastic lens. 
     An antireflection film having a high transmissivity over a wide wavelength range may be applied to the lens surfaces of the lenses constituting the zoom optical system of the present application. This reduces flares and ghosts, and can achieve a high optical performance having a high contrast. 
     According to the configurations described above, this camera  1  mounted with the zoom optical system according to the first example as the imaging lens  2  can achieve high-speed AF and silence during AF without increasing the size of the lens barrel, by reducing the size and weight of the focusing lens group, can favorably suppresses variation of aberrations upon zooming from the wide-angle end state to the telephoto end state, and variation of aberrations upon focusing from an infinite distant object to a short distant object, and can achieve a favorable optical performance. Note that possible configurations of cameras mounted with the zoom optical systems according to the second to seventh examples described above as the imaging lens  2  can also exert the advantageous effects analogous to those of the camera  1  described above. 
     
       
         
           
               
             
               
                   
               
               
                 EXPLANATION OF NUMERALS AND CHARACTERS 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 G1 First lens group 
                 G2 Second lens group 
               
               
                   
                 G3 Third lens group 
                 G4 Fourth lens group 
               
               
                   
                 G5 Fifth lens group 
                 GFS Front lens group 
               
               
                   
                 GM1 M1 lens group 
                 GM2 M2 lens group 
               
               
                   
                 GRN RN lens group 
               
               
                   
                 I Image surface 
                 S Aperture stop