Patent Publication Number: US-11385446-B2

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

Description:
TECHNICAL FIELD 
     The present invention relates to a zoom optical system, an optical device and a method for manufacturing the zoom optical system. 
     TECHNICAL BACKGROUND 
     Conventionally, many zoom optical systems in which a lens group arranged closest to an object has positive refractive power are proposed as a zoom optical system suitable for an interchangeable lens for a camera, a digital camera, a video camera, etc. (for example, refer to Patent Document 1). 
     An optical system, in which focusing is performed by moving part of a lens group along an optical axis, is proposed from among these zoom optical systems. 
     Many methods for correcting image blur, in which an image is moved in a direction perpendicular to an optical axis by moving a lens group in the direction perpendicular to the optical axis, are proposed. 
     PRIOR ART LIST 
     Patent Document 
     
         
         [Patent Document 1] Japanese Laid-Open Patent Publication No. H8-179214 (A) 
       
    
     SUMMARY OF THE INVENTION 
     Means to Solve the Problems 
     A zoom optical system according to a first invention, comprises, in order from an object, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group, and a distance between the first lens group and the second lens group, a distance between the second lens group and the third lens group, a distance between the third lens group and the fourth lens group, and a distance between the fourth lens group and the fifth lens group change upon zooming, and a lens group arranged closest to an image is approximately fixed against an image surface upon zooming, and the third lens group moves along the optical axis upon focusing, and the following conditional expression is satisfied.
 
4.80 &lt;f 3 /ft &lt;4.000
 
     where, ft denotes a focal length of the zoom optical system in a telephoto end state, and f3 denotes a focal length of the third lens group. 
     An optical device according to the first invention is equipped with the zoom optical system according to the first invention. 
     A method for manufacturing a zoom optical system according to the first invention, the zoom optical system comprises, in order from an object, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group, and each lens is disposed in a lens-barrel so that a distance between the first lens group and the second lens group, a distance between the second lens group and the third lens group, a distance between the third lens group and the fourth lens group, and a distance between the fourth lens group and the fifth lens group change upon zooming, and a lens group arranged closest to an image is fixed against an image surface upon zooming, and the third lens group moves along the optical axis upon focusing, and the following conditional expressions is satisfied.
 
0.480 &lt;f 3/ ft&lt; 4.000
 
     wherein ft denotes a focal length of the zoom optical system in a telephoto end state, and 
     f3 denotes a focal length of the third lens group. 
     A zoom optical lens according to a second invention comprises, in order from an object, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group, and a distance between the first lens group and the second lens group, a distance between the second lens group and the third lens group, a distance between the third lens group and the fourth lens group, and a distance between the fourth lens group and the fifth lens group change upon zooming, and a lens group arranged closest to an image is approximately fixed against an image surface upon zooming, and the following conditional expressions are satisfied.
 
0.480&lt; f 3/ ft&lt; 4.000
 
−0.100&lt;( d 3 t−d 3 w ) /fw&lt; 0.330
 
     where, ft denotes a focal length of the zoom optical system in a telephoto end state, 
     f3 denotes a focal length of the third lens group, 
     fw denotes a focal length of the zoom optical system in a wide-angle end state, 
     d3w a distance on the optical axis from a lens surface arranged closest an image side of the third lens group in a wide-angle end state to a lens surface arranged closest to an object side of the fourth lens group, and 
     d3t denotes a distance on the optical axis from a lens surface arranged closest to the image side of the third lens group in a telephoto end state to a lens surface arranged closest to the object side of the fourth lens group. 
     An optical device according to the second invention is equipped with the zoom optical system according to the second invention. 
     A method for manufacturing a zoom optical system according to the second invention comprises, in order from an object, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group, and each lens is disposed in a lens-barrel so that a distance between the first lens group and the second lens group, a distance between the second lens group and the third lens group, a distance between the third lens group and the fourth lens group, and a distance between the fourth lens group and the fifth lens group changing upon zooming, and a lens group arranged closest to an image is approximately fixed to an image surface upon zooming, and the following conditional expressions are satisfied.
 
0.480&lt; f 3/ ft&lt; 4.000
 
−0.100&lt;( d 3 t−d 3 w )/ fw&lt; 0.330
 
     where, ft denotes a focal length of the zoom optical system in a telephoto end state, 
     f3 denotes a focal length of the third lens group, 
     fw denotes a focal length of the zoom optical system in a wide-angle end state, 
     d3w denotes a distance on the optical axis from a lens surface arranged closest the image side of the third lens group in a wide-angle end state to a lens surface arranged closest to the object side of the fourth lens group, and 
     d3t denotes a distance on the optical axis from a lens surface arranged closest to the image side of the third lens group in a telephoto end state to a lens surface arranged closest to the object of the fourth lens group. 
     A zoom optical system according to a third invention comprises, in order from an object, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group, and a distance between the first lens group and the second lens group, a distance between the second lens group and the third lens group, a distance between the third lens group and the fourth lens group, and a distance between the fourth lens group and the fifth lens group change upon zooming, and a lens group arranged closest to an image is approximately fixed against an image surface upon zooming, and the fourth lens group comprises an aperture stop. 
     An optical device according to the third invention is equipped with the zoom optical system according to the third invention. 
     A method for manufacturing a zoom optical system according to the third invention comprises, in order from an object, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group, and each lens is disposed in a lens-barrel so that a distance between the first lens group and the second lens group, a distance between the second lens group and the third lens group, a distance between the third lens group and the fourth lens group, and a distance between the fourth lens group and the fifth lens group change upon zooming, and a lens group arranged closest to an image is approximately fixed against an image surface upon zooming, and the fourth lens group comprises an aperture stop. 
     A zoom optical system according to a fourth invention comprises, in order from an object, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having positive refractive power, and a distance between the first lens group and the second lens group, a distance between the second lens group and the third lens group, and a distance between the third lens group and the fourth lens group change upon zooming, and the fourth lens group comprises, in order from an object, a fourth A sublens group movable in a manner of having a component in a direction perpendicular to the optical axis in order to correct image blur and, and a fourth B sublens group. 
     The optical device according to a fourth invention carries the zoom optical system according to the fourth invention. 
     A method for manufacturing an zoom optical system according to a fourth invention, the zoom optical system comprising, in order from an object, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having positive refractive power, and each lens is disposed in a lens-barrel so that a distance between the first lens group and the second lens group, a distance between the second lens group and the third lens group, and a distance between the third lens group and the fourth lens group change upon zooming, and the fourth lens group comprises, in order from the object, a fourth A sublens group configured to enable to move in a manner of having a component in a direction perpendicular to the optical axis in order to correct image blur, and a fourth B sublens group. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates sectional views in a wide-angle end state (W), intermediate focal length state (M), and telephoto end state (T) of a zoom optical system according to Example 1. 
         FIGS. 2A, 2B, and 2C  respectively illustrate graphs showing various aberrations upon focusing on an infinity object in a wide-angle end state, intermediate focal length state, and telephoto end state of the zoom optical system according to Example 1. 
         FIGS. 3A, 3B, and 3C  respectively illustrate graphs showing various aberrations upon focusing on a short-distance object in a wide-angle end state, intermediate focal length state, and telephoto end state (1.00 m of a distance between object images) of the zoom optical system according to Example 1. 
         FIGS. 4A, 4B, and 4C  respectively illustrate graphs showing meridional lateral aberration when correcting image blur upon focusing on an infinity object in a wide-angle end state, intermediate focal length state, and telephoto end state of the zoom optical system according to Example 1 (shift amount of a vibration-free lens group=0.1 mm). 
         FIG. 5  illustrates sectional views in a wide-angle end state(W), intermediate focal length state(M), and telephoto end state(T) of the zoom optical system according to Example 2. 
         FIGS. 6A, 6B, and 6C  respectively illustrate graphs showing various aberration upon focusing on an infinity object in a wide-angle end state, intermediate focal length state, and telephoto end state of the zoom optical system according to Example 2. 
         FIGS. 7A, 7B, and 7C  respectively illustrate graphs showing various aberrations upon focusing a short-distance object in a wide-angle end state, intermediate focal length state, and telephoto end state (1.00 m of a distance between object images) of the zoom optical system according to Example 2. 
         FIGS. 8A, 8B, and 8C  respectively illustrate meridional lateral aberration when correcting image blur upon focusing on an infinity object in a wide-angle end state, intermediate focal length state, and telephoto end state of the zoom optical system according to Example 2 (shift amount of a vibration-free lens group=0.1 mm). 
         FIG. 9  illustrates sectional views in a wide-angle end state(W), intermediate focal length state(M), and telephoto end state(T) of the zoom optical system according to Example 3. 
         FIGS. 10A, 10B, and 10C  respectively illustrate graphs showing various aberrations upon focusing on an infinity object in a wide-angle end state, intermediate focal length state, and telephoto end state of the zoom optical system according to Example 3. 
         FIGS. 11A, 11B, and 11C  respectively illustrate graphs showing various aberrations upon focusing on a short-distance object in a wide-angle end state, intermediate focal length state, and telephoto end state of the zoom optical system according to Example 3 (1.00 m of a distance between images). 
         FIGS. 12A, 12B, and 12C  respectively illustrate graphs showing meridional lateral aberration when correcting image blur upon focusing on an infinity object focusing in a wide-angle end state, intermediate focal length state, and telephoto end state (shift amount of a vibration-free lens group=0.1 mm) of the zoom optical system according to Example 3. 
         FIG. 13  illustrates sectional views in a wide-angle end state(W), intermediate focal length state(M), and telephoto end state(T) of the zoom optical system according to Example 4. 
         FIGS. 14A, 14B, and 14C  respectively illustrate graphs showing various aberrations upon focusing on an infinity object in a wide-angle end state, intermediate focal length state, and telephoto end state of the zoom optical system according to Example 4. 
         FIGS. 15A, 15B, and 15C  respectively illustrate graphs showing various aberration upon focusing on a short-distance object focusing in a wide-angle end state, intermediate focal length state, and telephoto end state (1.00 m of a distance between object images) of the zoom optical system according to Example 4. 
         FIGS. 16A, 16B, and 16C  respectively illustrate meridional lateral aberration when correcting image blur upon focusing on an infinity object in a wide-angle end state, intermediate focal length state, and telephoto end state (shift amount of a vibration-free lens group=0.1 mm) of the zoom optical system according to Example 4. 
         FIG. 17  is a diagram illustrating a configuration of a camera comprising a zoom optical system according to each of Examples 1 to 4. 
         FIG. 18  is a diagram illustrating an outline of a method manufacturing a zoom optical system according to the first embodiment. 
         FIG. 19  is a diagram illustrating an outline of a method manufacturing a zoom optical system according to the second embodiment. 
         FIG. 20  is a diagram illustrating an outline of a method for manufacturing a zoom optical system according to the third embodiment. 
         FIG. 21  is a diagram illustrating an outline of a method for manufacturing a zoom optical system according to the fourth embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS (FIRST TO FOURTH EMBODIMENTS) 
     A first embodiment will be now described with reference to the drawings. A zoom optical system ZL according to the first embodiment comprises, as illustrated in  FIG. 1 , in order from an object along an optical axis, a first lens group G 1  having positive refractive power, a second lens group G 2  having negative refractive power, a third lens group G 3  having positive refractive power, a fourth lens group G 4  having positive refractive power, and a fifth lens group G 5 , and a distance between the first lens group G 1  and the second lens group G 2 , a distance between the second lens group G 2  and the third lens group G 3 , a distance between the third lens group G 3  and the fourth lens group G 4 , and a distance between the fourth lens group G 4  and the fifth lens group G 5  are configured to change upon zooming. With this arrangement, it is possible to realize zooming, and suppress respective fluctuations of distortion accompanying zooming, astigmatism, and spherical aberration. 
     The zoom optical system ZL according to the first embodiment is configured that a lens group arranged closest to an image (corresponding to the fifth lens group G 5  in  FIG. 1 ) is approximately fixed against an image surface I upon zooming. With this arrangement, it is possible to optimize a change of a height of an off-axial flux of light passing through the lens group arranged closest to the image upon zooming, and suppress a fluctuation of distortion or astigmatism. In addition, this enables to simplify a lens-barrel structure configuring the zoom optical system ZL according to the first embodiment, suppress decentering due to manufacturing errors, etc., and suppress inclination of a surrounding image surface and decentering coma aberration generated due to decentering of the lens group arranged closest to the image. 
     The zoom optical system ZL according to the first embodiment is configured that focusing is performed by moving the third lens group G 3  along the optical axis. With this arrangement, it is possible to suppress a fluctuation of astigmatism and spherical aberration upon focusing by suppressing amount of movement upon focusing on infinity, and suppressing a fluctuation of a height from the optical axis regarding light incident on the third lens group G 3  which is a focusing lens group in a telephoto end state. 
     In the zoom optical system ZL according to the first embodiment, the following conditional expression (1) is satisfied.
 
0.480&lt; f 3/ ft&lt; 4.000   (1)
 
     where, ft denotes a focal length of the zoom optical system ZL in a telephoto end state, and 
     f3 denotes a focal length of the third lens group G 3 . 
     The conditional expression (1) defines a range of an appropriate focal length of the third lens group G 3 . By satisfying the conditional expression (1), it is possible to suppress astigmatism and spherical aberration upon zooming. 
     When a corresponding value of the conditional expression (1) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of astigmatism and spherical aberration generated in the third lens group G 3  upon zooming, therefore high optical performance cannot be realized. When trying to suppress such aberration fluctuation, more configuration lenses are needed, therefore downsizing is not possible. 
     In order to further ensure the advantageous effect of the first embodiment, it is preferable to set the lower limit of the conditional expression (1) to 0.570. 
     When the corresponding value of the conditional expression (1) exceeds an upper limit, a fluctuation of astigmatism generated in the fourth lens group G 4  becomes excessive upon zooming, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the first embodiment, it is preferable that the upper limit of the conditional expression (1) is set to 0.3200. In order to additionally ensure the advantageous effect of the first embodiment, it is preferable to set the upper limit of the conditional expression (1) to 2.400. 
     In the zoom optical system ZL according to the first embodiment, it is preferable that the following conditional expression (2) is satisfied.
 
0.900&lt;(− f 2)/ fw&lt; 1.800   (2)
 
     where, fw denotes a focal length of the zoom optical system ZL in a wide-angle end state, and 
     f2 denotes a focal length of the second lens group G 2 . 
     The conditional expression (2) defines a range of an appropriate focal length of the second lens group G 2 . By satisfying the conditional expression (2), it is possible to suppress a fluctuation astigmatism and spherical aberration upon zooming. 
     When a corresponding value of the conditional expression (2) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of astigmatism and spherical aberration generated in the second lens group G 2  upon zooming, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the first embodiment, it is preferable to set the lower limit of the conditional expression (2) to 0.970. In order to additionally ensure the advantageous effect of the first embodiment, it is preferable to set the lower limit of the conditional expression (2) to 1.065. 
     When a corresponding value of the conditional expression (2) exceeds an upper limit, it is necessary to enlarge, in order to secure a predetermined zoom ratio, a distance change between the first lens group G 1  and the second lens group G 2  upon zooming. As a result, since a ratio of a diameter of an axial flux of light passing through the first lens group G 1  and the second lens group G 2  greatly changes, a fluctuation of spherical aberration upon zooming becomes excessive, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the first embodiment, it is preferable to set the upper limit of the conditional expression (2) to 1.600. 
     In the zoom optical system ZL according to the first embodiment, it is preferable that the following conditional expression (3) is satisfied.
 
0.600&lt; f 3/ f 4&lt;4.000   (3)
 
     where, f4 denotes a focal length of the fourth lens group G 4 . 
     The conditional expression (3) defines a range of an appropriate focal length of the third lens group and the fourth lens group G 4 . By satisfying the conditional expression (3), it is possible to suppress a fluctuation of astigmatism and spherical aberration upon focusing. 
     When a corresponding value of the conditional expression (3) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of astigmatism and spherical aberration generated in the third lens group G 3  upon focusing, therefore high optical performance is not realized. 
     In order to further ensure the advantageous effect of the first embodiment, it is preferable that the lower limit of the conditional expression (3) is set to 0.840. In order to additionally ensure the advantageous effect of the first embodiment, it is preferable that the lower limit of a conditional expression (3) is set to 0.970. 
     When a corresponding value of the conditional expression (3) exceeds an upper limit, it is necessary to greatly change, in order to secure a predetermined focusing range, a distance between the third lens group and the fourth lens group G 4  upon focusing. As a result, since a diameter of an axial flux of light passing through the third lens group greatly changes, a fluctuation of spherical aberration upon focusing becomes excessive, therefore high optical performance is not realized. 
     In order to further ensure the advantageous effect of the first embodiment, it is preferable to set the upper limit of the conditional expression (3) to 2.880. 
     In the zoom optical system ZL according to the first embodiment, it is preferable that only the third lens group G 3  moves along the optical axis upon focusing. With this arrangement, compared to a case in which focusing is performed with a plurality of lenses, it is possible to suppress mutual decentering when manufacturing between focusing lens groups upon focusing, and suppress generating decentering coma aberration, therefore high optical performance can be realized. 
     In the zoom optical system ZL according to the first embodiment, t is preferable that the third lens group G 3  is composed of one lens component. With this arrangement, it is possible to downsize the focusing lens groups, and suppress a fluctuation of spherical aberration upon focusing. This configuration can contribute to speeding up upon focusing. 
     In the zoom optical system ZL according to the first embodiment, it is preferable that the third lens group G 3  is composed of one single lens. With this arrangement, it is possible to downsize the focusing lens group. This configuration can contribute to speeding up upon focusing. Because lenses configuring the third lens group G 3  are not composed of a plurality of and cementing lenses, it is possible to relatively suppress influence of decentering coma aberration, etc. due to decentering of mutual lenses, therefore higher optical performance can be realized. 
     In the zoom optical system ZL according to the first embodiment, it is preferable that the third lens group G 3  comprises a lens made from an optical material satisfying the following conditional expression (4).
 
48.00&lt; v 3   (4)
 
     where, v3 denotes an Abbe number on the basis of d-line of the optical material used for the lens configuring the third lens group G 3 . 
     The conditional expression (4) defines a range of an appropriate Abbe number of an optical material used for the lens configuring the third lens group G 3 . When a corresponding value of the conditional expression (4) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of chromatic aberration upon focusing, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the first embodiment, it is preferable that the lower limit of the conditional expression (4) is set to 55.00. In order to additionally ensure the advantageous effect of the first embodiment, it is preferable that the lower limit of a conditional expression (4) is set to 58.00. 
     In order to further ensure the advantageous effect of the first embodiment, it is preferable that the upper limit of a conditional expression (4) is set to 90.00. In order to further ensure the advantageous effect of the first embodiment, it is preferable that the upper limit of a conditional expression (4) is set to 75.00. 
     In the zoom optical system ZL according to the first embodiment, it is preferable that in the third lens group G 3  at least one surface is aspherical-shaped. With this arrangement, it is possible to suppress a fluctuation of astigmatism and spherical aberration upon zooming and focusing. 
     In the zoom optical system ZL according to the first embodiment, it is preferable that the following conditional expression (5) is satisfied.
 
−0.050&lt;( d 3 t−d 3 w )/ fw&lt; 0.330   (5)
 
     where, fw denotes a focal length of the zoom optical system ZL in a wide-angle end state, 
     d3w denotes a distance on the optical axis from a lens surface arranged closest to the image side of the third lens group G 3  in a wide-angle end state to a lens surface arranged closest to an object side of the fourth lens group G 4 , and 
     d3t denotes a distance on the optical axis from the lens surface arranged closest to the image side of the third lens group G 3  in a telephoto end state to the lens surface arranged closest to the object side of the fourth lens group G 4 . 
     The conditional expression (5) defines an appropriate range of a distance change between the third lens group G 3  and the fourth lens group G 4  upon zooming. By satisfying the conditional expression (5), it is possible to suppress a fluctuation of astigmatism upon zooming. 
     When a corresponding value of the conditional expression (5) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of astigmatism generated in the third lens group G 3  upon zooming, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the first embodiment, it is preferable that the lower limit of a conditional expression (5) is set to 0.010. 
     When a corresponding value of the conditional expression (5) exceeds an upper limit, a change of height from the optical axis of an off-axial flux of light passing through the fourth lens group G 4  upon zooming becomes large, therefore a fluctuation of astigmatism generated in the fourth lens group G 4  becomes excessive, thereby high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the first embodiment, it is appreciated that the upper limit of a conditional expression (5) is set to 0.275. 
     In the zoom optical system ZL according to the first embodiment, it is preferable the fourth lens group G 4  has an aperture stop S. With this arrangement, it is possible to suppress a fluctuation of astigmatism generated in the fourth lens group G 4 , thereby high optical performance can be realized. 
     In the zoom optical system ZL according to the first embodiment, it is preferable that the aperture stop S is disposed between the third lens group G 3  and the fourth lens group G 4 . With this arrangement, a change in a height direction from the optical axis of the off-axial flux of light passing through the third lens group G 3  and the fourth lens group G 4  upon zooming can be reduced, therefore a fluctuation of astigmatism generated in the third lens group G 3  and the fourth lens group G 4  can be suppressed, thereby high optical performance can be realized. 
     In the zoom optical system ZL according to the first embodiment, it is preferable that the following conditional expression (6) is satisfied.
 
0.470&lt; f 4/ ft&lt; 0.900   (6)
 
     where, f4 denotes a focal length of the fourth lens group G 4 . 
     The conditional expression (6) defines a range of an appropriate focal length of the fourth lens group G 4 . By satisfying the conditional expression (6), it is possible to suppress a fluctuation of astigmatism and spherical aberration upon zooming. 
     When a corresponding value of the conditional expression (6) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of astigmatism and spherical aberration generated in the fourth lens group G 4  upon zooming, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the first embodiment, it is preferable that the lower limit of the conditional expression (6) is set to 0.530. 
     When a corresponding value of the conditional expression (6) exceeds an upper limit, it is necessary to enlarge, in order to secure a predetermined zoom ratio, amount of movement of the fourth lens group G 4  against the image surface I upon zooming. As a result, since a diameter of an axial flux of light passing through the fourth lens group G 4  greatly changes, a fluctuation of the spherical aberration upon zooming becomes excessive, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the first embodiment, it is preferable that the upper limit of the conditional expression (6) is set to 0.720. 
     In the zoom optical system ZL according to the first embodiment, it is preferable that a lens group arranged closest to the image has positive refractive power. With this arrangement, magnification used in the lens arranged closest to the image becomes less than 100%, therefore it is possible to relatively enlarge a composite focal length of the lens group arranged closer to the object (for example, corresponding to the first lens group G 1  to the fourth lens group G 4  in  FIG. 1 ) rather than the lens group arranged closest to the image. As a result, it is possible to relatively suppress influence of decentering coma aberration, etc. generated due to decentering between lenses, generated in the lens arranged closer to the object side rather than the lens group arranged closest to the image when manufacturing, therefore high optical performance can be realized. 
     In the zoom optical system ZL according to the first embodiment, it is appreciated that the following conditional expression (7) is satisfied.
 
3.000&lt; fR/fw&lt; 9.500   (7)
 
     where, fw denotes a focal length of the zoom optical system ZL in a wide-angle end state, and 
     fR denotes a focal length of the lens group arranged closest to the image. 
     The conditional expression (7) defines a range of an appropriate focal length of the lens group arranged closest to the image. By satisfying the conditional expression (7), it is possible to suppress a fluctuation of distortion and astigmatism upon zooming. 
     When a corresponding value of the conditional expression (7) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of distortion and astigmatism generated in the lens group arranged closest to the image upon zooming, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the first embodiment, it is preferable that the lower limit of the conditional expression (7) is set to 4.200. 
     When a corresponding value of the conditional expression (7) exceeds an upper limit, it becomes difficult to correct, by the lens group arranged closest to the image, a fluctuation of astigmatism generated in a lens group arranged closer to the object rather than the lens group arranged closest to the image, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the first embodiment, it is preferable that the upper limit of the conditional expression (7) is set to 7.600. 
     In the zoom optical system ZL according to the first embodiment, it is preferable that the lens group arranged closest to the image is the fifth lens group G 5 . With this arrangement, it is possible to appropriately correct a fluctuation of spherical aberration upon zooming. 
     In the zoom optical system ZL according to the first embodiment, the lens group arranged closest to the image can configure a sixth lens group G 6 . With this arrangement, it is possible to appropriately correct a fluctuation of astigmatism upon zooming. 
     In the zoom optical system ZL according to the first embodiment, it is preferable that the third lens group G 3  moves to an image side upon focusing from an infinity object to a short-distance object. With this arrangement, it is possible to focus only with the third lens group G 3 , and suppress a fluctuation of astigmatism and spherical aberration upon focusing while downsizing the focusing lens group, therefore high optical performance can be realized. 
     In the zoom optical system ZL according to the first embodiment, it is preferable that the first lens group G 1  moves to the object side upon zooming from a wide-angle end state to a telephoto end state. With this arrangement, it is possible to suppress a change of a height from the optical axis of the off-axial flux of light passing through the first lens group G 1  upon zooming. As a result, it is possible to suppress a fluctuation of astigmatism upon zooming, generated in the first lens group G 1 . Note that the first lens group G 1  may monotonically move to the object side, or move in a manner of drawing a locus of a convex may on the image side. 
     In the zoom optical system ZL according to the first embodiment, it is preferable that a distance between the first lens group G 1  and the second lens group G 2  increases upon zooming from a wide-angle end state to a telephoto end state. With this arrangement, since magnification of the second lens group G 2  can be enlarged upon zooming from the wide-angle end state to the telephoto end state, a focal length of all lens groups can be configured to be long, therefore it is possible to suppress a fluctuation of astigmatism and spherical aberration upon zooming. 
     In the zoom optical system ZL according to the first embodiment, it is preferable that a distance between the second lens group G 2  and the third lens group G 3  decreases upon zooming from a wide-angle end state to a telephoto end state. With this arrangement, since composite magnification up to the lens group arranged closest to the image from the third lens group G 3  upon zooming from the wide-angle end state to the telephoto end state, a focal length of all lens groups can be configured to be long, therefore it is possible to suppress a fluctuation of astigmatism and spherical aberration upon zooming. 
     In the zoom optical system ZL according to the first embodiment, it is preferable that the second lens group G 2  moves to the object side upon zooming from a wide-angle end state to a telephoto end state. With this arrangement, downsizing can be attained. Additionally, this configuration enables to suppress a fluctuation of astigmatism and spherical aberration upon zooming. Note that the second lens group G 2  may monotonically move to the object side, or move in a manner of drawing a locus of a convex on the image side. 
     According to the zoom optical system ZL according to the first embodiment equipped with the configurations above, it is possible to realize the zoom optical system having high optical performance upon zooming and focusing. 
     Next, referring of  FIG. 17 , a camera (optical device) equipped with the above zoom optical system ZL is described. A camera  1  is, as shown in  FIG. 17 , a lens-interchangeable camera (so-called mirror-less camera) equipped with the above zoom optical system ZL as a photographing lens  2 . In this camera  1 , light from an unillustrated object (photographic subject) is condensed by the photographing lens  2 , and configures a photographic subject image on an imaging surface of an imaging unit  3  via an unillustrated OLPF (Optical Low Pass Filter). A picture of the photographic subject is created by photoelectrically converting the photographic subject by a photoelectric conversion element provided in the imaging unit  3 . This picture is displayed on a EVF (Electronic View Finder)  4  provided in the camera  1 . With this arrangement, it is possible to observe the photographing subject via the EVF  4 . When an unillustrated release button is pressed by a photographer, an image of the photographic subject taken by the imaging unit  3  is memorized in an unillustrated memory. Accordingly, the photographer can shoot the photographic subject by the camera  1 . 
     The zoom optical system ZL according to the first embodiment equipped with in the camera  1  as the photographing lens  2  has, as found based each example mentioned below, high optical performance upon zooming and focusing by means of characteristic lens configurations. Therefore, according to the camera  1  according to the first embodiment, an optical device having high optical performance can be realized upon zooming and focusing. 
     Note that in case of installing the above zoom optical system ZL on a single-lens-reflex-type camera having a quick return mirror and observing a photographic subject with a finder optical system, the same advantageous effect as the above camera  1  can be obtained. In case of installing the zoom optical system ZL on a video camera, the same advantageous effect as the camera  1  can be obtained as well. 
     Next, referring to  FIG. 18 , a method for manufacturing the above zoom optical system ZL will be outlined. Firstly, each lens is disposed in a lens-barrel so that a first lens group G 1  having positive refractive power, a second lens group G 2  having negative refractive power, a third lens group G 3  having positive refractive power, a fourth lens group G 4  having positive refractive power, and a fifth lens group G 5  are arranged in order from an object (Step ST 110 ). At this point, each lens is disposed so that a distance between the first lens group G 1  and the second lens group G 2 , a distance between the second lens group G 2  and the third lens group G 3 , a distance between the third lens group and the fourth lens group G 4 , and a distance between the fourth lens group G 4  and the fifth lens group G 5  change upon zooming (Step ST 120 ). Each lens is disposed so that a lens group arranged closest to the image is approximately fixed against an image surface upon zooming (Step ST 130 ). Each lens is disposed so that the third lens group moves along the optical axis upon zooming (Step ST 140 ). Each lens is arranged so that at least a conditional expression (1) among the conditional expressions is satisfied (Step ST 150 ).
 
0.480&lt; f 3/ ft&lt; 4.000   (1)
 
where, ft denotes a focal length of the zoom optical system ZL in a telephoto end state, and
 
     f3 denotes a focal length of the third lens group G 3 . 
     Exampling a lens arrangement according to the first embodiment, in the zoom optical system ZL illustrated in  FIG. 1 , as the first lens group G 1  having positive refractive power, a cemented lens composed of a negative meniscus lens L 11  having a concave surface facing the object and a biconvex positive lens L 12 , and a positive meniscus lens L 13  having a convex surface facing an object are disposed in a lens-barrel in order from the object along the optical surface. As the second lens group G 2  having negative refractive power, a negative meniscus lens L 21  having a convex surface facing the object, a biconcave negative lens L 22 , and a biconvex positive lens L 23  are disposed in the lens-barrel in order from the object along the optical axis. As the third lens group G 3  having positive refractive power, a biconvex positive lens L 31  is disposed in the lens-barrel. As the fourth lens group G 4  having positive refractive power, a cemented lens composed of a negative meniscus lens L 41  having a convex surface facing the object and a biconvex positive lens L 42 , a cemented lens composed of a biconvex positive lens L 43  and a negative meniscus lens L 44  having a concave surface facing the object, and a negative meniscus lens L 45  having a convex surface facing the object are disposed in the lens-barrel in order from an object along the optical axis. As the fifth lens group G 5 , a positive meniscus lens L 51  having a concave surface facing the object is disposed in the lens-barrel. Each lens is disposed in the lens-barrel so that the conditional expression (1) is satisfied (a corresponding value of the conditional expression (1) is 1.031). 
     According to the method for manufacturing the zoom optical system according to the first embodiment, it is possible to manufacture the zoom optical system ZL having high optical performance upon zooming and focusing. 
     As described above, according to the first embodiment, it is possible to solve a problem owned by a conventional zoom optical system, such that it is difficult to sufficiently maintain high optical performance upon focusing. 
     Next, a second embodiment is described with reference to the drawings. A zoom optical system ZL according to the second embodiment comprises, as illustrated in  FIG. 1 , in order from the object along the optical axis, a first lens group G 1  having positive refractive power, a second lens group G 2  having negative refractive power, a third lens group having positive refractive power, a fourth lens group G 4  having positive refractive power, and a fifth lens group G 5 , wherein upon zooming, and a distance between the first lens group G 1  and the second lens group G 2 , a distance between the second lens group G 2  and the third lens group G 3 , a distance between the third lens group G 3  and the fourth lens group G 4 , and a distance between the fourth lens group G 4  and the fifth lens group G 5  are configured to change upon zooming. With this arrangement, it is possible to suppress respective fluctuations such as distortion accompanying zooming, astigmatism, and spherical aberration. 
     In the zoom optical system ZL according to the second embodiment, a lens group arranged closest to the image (corresponding to the fifth lens group G 5  in  FIG. 1 ) is approximately fixed against the image surface I upon zooming. With this arrangement, a change of a height of the axial outside flux of light passing through the lens group arranged closest to the image is optimized upon zooming, therefore it is possible to suppress a fluctuation of distortion and astigmatism. In addition, this configuration enables to simplify a lens-barrel structure configuring the zoom optical system ZL according to the second embodiment, and suppress eccentricity due to manufacturing errors, etc., therefore it is possible to suppress inclination of surrounding an image surface and eccentricity coma aberration generated in generated due to eccentricity of the lens group arranged closest to the image. 
     In the zoom optical system ZL according to the second embodiment the following conditional expression (8) is satisfied.
 
0.480&lt; f 3/ ft&lt; 4.000   (8)
 
where, ft denotes a focal length of the zoom optical system ZL in a telephoto end state, and
 
     f3 denotes a focal length of the third lens group G 3 . 
     The conditional expression (8) defines a range of an appropriate focal length of the third lens group G 3 . By satisfying the conditional expression (8), it is possible to suppress a fluctuation of astigmatism and spherical aberration upon zooming. 
     When a corresponding value of the conditional expression (8) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of astigmatism and spherical aberration generated in the third lens group G 3  upon zooming, thereby high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the second embodiment, it is preferable that the lower limit of the conditional expression (8) is set to 0.570. 
     When a corresponding value of the conditional expression (8) exceeds upper limit, a fluctuation of astigmatism generated in the fourth lens group G 4  becomes excessive upon zooming, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the second embodiment, it is preferable that set the upper limit of a conditional expression (8) is set to 3.200. In order to additionally ensure the advantageous effect of the second embodiment, it is preferable that the upper limit of the conditional expression (8) si set to 2.400. 
     In the zoom optical system ZL according to the second embodiment the following conditional expression (9) is satisfied.
 
−0.100&lt;( d 3 t−d 3 w ) /fw&lt; 0.330   (9)
 
     where, fw denotes a focal length of the zoom optical system ZL in a wide-angle end state, 
     d3w denotes a distance on the optical axis from a lens surface arranged closest to the image side of the third lens group G 3  in the wide-angle end state to a lens surface arranged closest to the object side of the fourth lens group G 4 , and 
     d3t denotes a distance on the optical axis from the lens surface arranged closest to the image side of the third lens group G 3  in a telephoto end state to the lens surface arranged closest to the object side of fourth lens group G 4 . 
     The conditional expression (9) defines an appropriate range the distance between the third lens group G 3  and the fourth lens group G 4  upon zooming. By satisfying the conditional expression (9), a fluctuation of astigmatism upon zooming can be suppressed. 
     When a corresponding value of the conditional expression (9) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of astigmatism generated in the third lens group G 3  upon zooming, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the second embodiment, it is preferable that the lower limit of the conditional expression (9) is set to −0.080. 
     When a corresponding value of the conditional expression (9) exceeds an upper limit, a change of a height from the optical axis of the axial flux of light passing through the fourth lens group G 4  upon zooming becomes large, therefore a fluctuation of astigmatism generated in the fourth lens group G 4  becomes excessive, thereby high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the second embodiment, it is preferable that the upper limit of the conditional expression (9) is set to 0.275. 
     In the zoom optical system ZL according to the second embodiment, it is most preferable that the lens group arranged closest to the image has positive refractive power. With this arrangement, magnification used in the lens group arranged closest to the image becomes less 100%, therefore a composite focal length of the lens group arranged closer to the object than the lens group arranged closest to the image (for example, corresponding to the first lens group G 1  to the fourth lens group G 4  in  FIG. 1 ) can be relatively enlarged. As a result, it is possible to relatively suppress influence of decentering coma aberration, etc. due to decentering of lenses generated in the lens group arranged closer to the object than the lens group arranged closest to the image when manufacturing, therefore high optical performance can be realized. 
     In the zoom optical system ZL according to the second embodiment, it is preferable that the following conditional expression (10) is satisfied.
 
3.000&lt; fR/fw&lt; 9.500   (10)
 
     where, fR denotes a focal length of the lens group arranged closest to the image. 
     The conditional expression (10) defines a range of an appropriate focal length of the lens group arranged closest to the image. By satisfying the conditional expression (10), a fluctuation of distortion and astigmatism upon zooming can be suppressed. 
     When a corresponding value of the conditional expression (10) is less than a lower limit, it becomes difficult to suppress a fluctuation of distortion and astigmatism generated in the lens group arranged closest to the image upon zooming, thereby high optical performance is realized. 
     In order to further ensure the advantageous effect of the second embodiment, it is preferable that the lower limit of the conditional expression (10) is set to 4.200. 
     When a corresponding value of the conditional expression (10) exceeds an upper limit, it becomes difficult to correct a fluctuation of astigmatism generated in the lens group arranged closer to the object side than the lens group arranged closest to the image, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the second embodiment, it is preferable that the upper limit of the conditional expression (10) is set to 7.600. 
     In the zoom optical system ZL according to the second embodiment, it is preferable the following conditional expression (11) is satisfied.
 
0.730&lt;(− f 2)/ fw&lt; 1.800   (11)
 
     where, f2 denotes a focal length of the second lens group G 2 . 
     The conditional expression (11) defines a range of an appropriate focal length of the second lens group G 2 . By satisfying the conditional expression (11), a fluctuation of astigmatism and spherical aberration upon zooming can be suppressed. 
     When a corresponding value of the conditional expression (11) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of astigmatism and spherical aberration generated in the second lens group G 2  upon zooming, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the second embodiment, it is preferable that the lower limit of the conditional expression (11) is set to 0.900. In order to additionally ensure the advantageous effect of the second embodiment, it is preferable that the lower limit of the conditional expression (11) is set to 1.065. 
     When a corresponding value of the conditional expression (11) exceeds an upper limit, it is necessary to enlarge a distance between the first lens group G 1  and the second lens group G 2  upon zooming in order to secure a predetermined zoom ratio. As a result, since a ratio of a diameter of an axial flux of light passing through the first lens group G 1  and the second lens group G 2  greatly changes, therefore a fluctuation of spherical aberration upon zooming becomes excessive, thereby high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the second embodiment, it is preferable that the upper limit of the conditional expression (11) is set to 1.600. 
     In the zoom optical system ZL according to the second embodiment, it is preferable that the following conditional expression (12) is satisfied.
 
0.470&lt; f 4/ ft&lt; 0.900   (12)
 
     where, f4 denotes a focal length of the fourth lens group G 4 . 
     The conditional expression (12) defines a range of an appropriate focal length of the fourth lens group G 4 . By satisfying the conditional expression (12), a fluctuation of astigmatism and spherical aberration upon zooming can be suppressed. 
     When a corresponding value of the conditional expression (12) is less than a lower limit, it becomes difficult to suppress a fluctuation of astigmatism and spherical aberration generated in the fourth lens group G 4  upon zooming, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the second embodiment, it is preferable that the lower limit of the conditional expression (12) is set to 0.530. 
     When a corresponding value of the conditional expression (12) exceeds an upper limit, it is necessary to enlarge amount of movement of the fourth lens group G 4  against the image surface I upon zooming, in order to secure a predetermined zoom ratio. As a result, since a diameter of the axial flux of light passing through the fourth lens group G 4  greatly changes, a fluctuation of spherical aberration upon zooming becomes excessive, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the second embodiment, it is preferable that the upper limit of a conditional expression (12) is set to 0.720. 
     In the zoom optical system ZL according to the second embodiment, it is preferable that the first lens group G 1  moves to the object upon zooming from a wide-angle end state to a telephoto end state. With this arrangement, it is possible to suppress a height from the optical axis of the axial flux of light passing through the first lens group G 1  upon zooming. As a result, it impossible to suppress a fluctuation of astigmatism upon zooming generated in the first lens group G 1 . 
     In the zoom optical system ZL according to the second embodiment, it is preferable that a distance between the first lens group G 1  and the second lens group G 2  increases upon zooming from a wide-angle end state to a telephoto end state. With this arrangement, it is possible to double magnification of the second lens group G 2  upon zooming from a wide-angle end state to a telephoto end state, therefore a focal length of all the lens groups can have a long configuration, therefore a fluctuation of astigmatism and spherical aberration upon zooming can be suppressed. 
     In the zoom optical system ZL according to the second embodiment, it is preferable that a distance between the second lens group G 2  and the third lens group G 3  decreases upon zooming from a wide-angle end state to a telephoto end state. With this arrangement, since a composite magnification from the third lens group G 3  to the fifth lens group G 5  can be doubled upon zooming from a wide-angle end state to a telephoto end state, a focal length of all lens groups can be configured to be long, therefore a fluctuation of astigmatism and spherical aberration upon zooming can be suppressed. 
     In the zoom optical system ZL according to the second embodiment, it is preferable that the following conditional expression (13) is satisfied.
 
0.350&lt;( d 1 t−d 1 w )/ ft&lt; 0.800   (13)
 
     where, d1w denotes a distance on the optical axis from the lens surface arranged closest to the image side of the first lens group G 1  in a wide-angle end state to the lens surface arranged closest to the object side of the second lens group G 2 , and 
     d1t denotes a distance on the optical axis from the lens surface arranged closest to the image side of the first lens group G 1  in a telephoto end state to the lens surface arranged closest to the object side of the second lens group G 2 . 
     The conditional expression (13) defines an appropriate range of a change of a distance between the first lens group G 1  and the second lens group G 2  upon zooming. By satisfying the conditional expression (13), a fluctuation of coma aberration and astigmatism upon zooming can be suppressed. 
     When a corresponding value of the conditional expression (13) becomes less than a lower limit, it is necessary to improve refractive power of the first lens group G 1  and the second lens group G 2  in order to realize a predetermined zoom ratio. Then, it becomes difficult to suppress a fluctuation of coma aberration and astigmatism upon zooming, generated in the second lens group G 2 , therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the second embodiment, it is preferable that the lower limit of the conditional expression (13) is set to 0.380. 
     When a corresponding value of the conditional expression (13) exceeds an upper limit, a change of a height from the optical axis of the axial flux of light passing through the first lens group G 1  upon zooming becomes large, therefore a fluctuation of astigmatism generated in the first lens group G 1  becomes excessive, thereby high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the second embodiment, it is preferable that the upper limit of a conditional expression (13) is set to 0.650. 
     In the zoom optical system ZL according to the second embodiment, it is preferable that the following conditional expression (14) is satisfied.
 
0.200&lt;( d 2 w−d 2 t )/ ft&lt; 0.700   (14)
 
     where, d2w denotes a distance on the optical axis from the lens surface arranged closest to the image side of the second lens group G 2  in a wide-angle end state to the lens surface arranged closest to the object side of the third lens group G 3 , and 
     d2t denotes a distance on the optical axis from the lens surface arranged closest to the image side of the second lens group G 2  in a telephoto end state to the lens surface arranged closest to the object to the third lens group G 3 . 
     The conditional expression (14) defines an appropriate range of a change of a distance between the second lens group G 2  and the third lens group upon zooming. By satisfying the conditional expression (14), a fluctuation of astigmatism and spherical aberration upon zooming can be suppressed. 
     When a corresponding value of the conditional expression (14) becomes less than a lower limit, it is necessary to improve refractive power of the second lens group G 2  and the third lens group in order to realize a predetermined zoom ratio. Then, it becomes difficult to suppress a fluctuation of astigmatism and spherical aberration upon zooming generated in the second lens group G 2  and the third lens group G 3 , therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the second embodiment, it is preferable that the lower limit of the conditional expression (14) is set to 0.270. 
     When a corresponding value of the conditional expression (14) exceeds an upper limit, a change of a height from the optical axis of an off-axial flux of light passing through the second lens group G 2  upon zooming becomes large, therefore a fluctuation of astigmatism generated in the second lens group G 2  becomes excessive, thereby high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the second embodiment, it is preferable that the upper limit of the conditional expression (14) is set to 0.550. 
     In the zoom optical system ZL according to the second embodiment, it is preferable that the fourth lens group G 4  has an aperture stop S. With this arrangement, it is possible to suppress a fluctuation of astigmatism generated in the fourth lens group G 4 , therefore high optical performance can be realized. 
     In the zoom optical system ZL according to the second embodiment, it is preferable that the aperture stop S is disposed between the third lens group G 3  and the fourth lens group G 4 . With this arrangement, a change of a height from the optical axis of off-axis flux of light passing tough the third lens group G 3  and the fourth lens group G 4  upon zooming can be reduced, therefore a fluctuation of astigmatism generated in the third lens group G 3  and the fourth lens group G 4  can be suppressed, thereby high optical performance can be realized. 
     In the zoom optical system ZL according to the second embodiment, it is preferable that the third lens group G 3  moves along the optical axis upon focusing. With this arrangement, amount of movement on a telephoto side upon focusing is suppressed, a fluctuation of the height from the optical axis regarding light incident on the third lens group G 3  which is a focusing lens group on the telephoto side is suppressed, therefore a fluctuation of astigmatism and spherical aberration upon focusing can be suppressed. 
     In the zoom optical system ZL according to the second embodiment, it is preferable that the third lens group G 3  moves to the image upon focusing from an infinity object to a short-distance object. With this arrangement, it becomes possible to focus only with the third lens group G 3 , a fluctuation of astigmatism and spherical aberration upon focusing can be suppressed, therefore high optical performance can be realized. 
     According to the zoom optical system ZL according to the second embodiment equipped with the above configuration, it is possible to realize the zoom optical system which has high optical performance over a whole zoom range. 
     Next, referring to  FIG. 17 , a camera (optical device) equipped with the zoom optical system ZL is described. This camera  1  has the same configurations as those of the first embodiment, and its configurations have already been described, the explanation is omitted here. 
     As found in each example mentioned below, the zoom optical system ZL according to the second embodiment equipped on the camera  1  as the photographing lens  2  has high optical performance over the whole zoom range. Thus, according to the camera  1  according to the second embodiment, it is possible to realize an optical device has high optical performance over the whole zoom range. 
     Note that in case of installing the zoom optical system ZL mentioned above on a single lens reflex type camera having a quick return mirror and observing a photographic subject with a finder optical system, the same advantageous effect as the above camera  1  can be obtained. In case of installing the zoom optical system ZL on a video camera, the same advantageous effect as the camera  1  can be obtained. 
     Next, referring to  FIG. 19 , a method for manufacturing the zoom optical system ZL is outlined. Firstly, each lens is disposed in a lens-barrel so that a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group are arranged in order from an object (Step ST 210 ). At this point, each lens is disposed in the lens-barrel so that a distance between the first lens group G 1  and the second lens group G 2 , a distance between the second lens group G 2  and the third lens group G 3 , a distance between the third lens group and the fourth lens group G 4 , and a distance between the fourth lens group G 4  and the fifth lens group G 5  change upon zooming (Step ST 220 ). Each lens is disposed so that the lens group arranged closest to the image is approximately fixed against an image surface upon zooming (Step ST 230 ). Each lens is arranged so that st least the conditional expressions (8) and (9) among the above conditional expressions are satisfied (Step ST 240 ).
 
0.480&lt; f 3/ ft&lt; 4.000   (8)
 
−0.100&lt;( d 3 t−d 3 w ) /fw&lt; 0.330   (9)
 
     where, ft denotes a focal length of the zoom optical system ZL in a telephoto end state, 
     f3 denotes a focal length of the third lens group G 3 , 
     fw denotes a focal length of the zoom optical system ZL in a wide-angle end state, 
     d3w denotes a distance on the optical axis from a lens surface arranged closest to the image side of the third lens group G 3  in a wide-angle end state to a lens surface arranged closest to the object side of the fourth lens group G 4 , and 
     d3t denotes a distance on the optical axis from the lens surface arranged closest to the image side of the third lens group G 3  in a telephoto end state to the lens surface arranged closest to the object side of the fourth lens group G 4 . 
     Exampling a lens arrangement according to the second embodiment, in the zoom optical system ZL illustrated in  FIG. 1 , as the first lens group G 1  having positive refractive power, a cemented lens composed of a negative meniscus lens L 11  having a convex surface facing an object and a biconvex positive lens L 12 , and a positive meniscus lens L 13  having a convex surface facing the object are disposed in a lens-barrel, in order from the object along the optical axis. As the second lens group G 2  having negative refractive power, a negative meniscus lens L 21  having a convex surface facing the object, a biconcave negative lens L 22 , and a biconvex positive lens L 23  are disposed in the lens-barrel, in order from the object along the optical axis. As the third lens group G 3  having positive refractive power, a biconvex positive lens L 31  is disposed in the lens-barrel. As the fourth lens group G 4  having positive refractive power, a cemented lens composed of a negative meniscus lens L 41  having a convex surface facing the object and a biconvex positive lens L 42 , a cemented lens composed of a biconvex positive lens L 43  and a negative meniscus lens L 44  having a concave surface facing the object, and a negative meniscus lens L 45  having a convex surface facing the object are disposed in the lens-barrel, in order from the object along the optical axis. As the fifth lens group G 5 , a positive meniscus lens L 51  having a concave surface facing the object is arranged in the lens-barrel. Each lens is disposed in the lens-barrel so that the conditional expressions (8) and (9) are satisfied (the corresponding value of the conditional expression (8) is 1.031, and the corresponding value of the conditional expression (9) is 0.215). 
     According to the method for manufacturing the zoom optical system according to the second embodiment, it is possible to manufacture the zoom optical system ZL having high optical performance over the whole zoom range. 
     As described above, according to the second embodiment, it is possible to solve a problem owned by a conventional zoom optical system such that it is difficult to sufficiently maintain high optical performance over a whole zoom range upon focusing. 
     Next, a third embodiment is described with referred to drawings. The zoom optical system ZL according to the third embodiment is configured to comprise, as illustrated in  FIG. 1 , in order from an object along an optical axis, a first lens group G 1  having positive refractive power, a second lens group G 2  having negative refractive power, a third lens group G 3  having positive refractive power, a fourth lens group G 4  having positive refractive power, and a fifth lens group G 5 , and a distance between the first lens group G 1  and the second lens group G 2 , a distance between the second lens group G 2  and the third lens group G 3 , a distance between the third lens group G 3  and the fourth lens group G 4 , and a distance between the fourth lens group G 4  and the fifth lens group G 5  are configured to change upon zooming. With this arrangement, it is possible to realize zooming, and suppress respective fluctuations of spherical aberration, astigmatism, and distortion accompanying zooming. 
     In the zoom optical system ZL according to the third embodiment, the lens group arranged closest to the image (corresponding to the fifth lens group G 5  in  FIG. 1 ) is approximately fixed against the image surface I, upon zooming. With this arrangement, a change of a height of the axial flux of light passing through the lens group arranged closest to the image, upon zooming, is optimized, therefore a fluctuation of astigmatism and distortion can be suppressed. In addition, this configuration enables to simplify a lens-barrel structure configuring the zoom optical system ZL according to the third embodiment, and suppress eccentricity due to manufacturing errors, etc., therefore it is possible to suppress inclination of surrounding an image surface and eccentricity coma aberration generated in generated due to eccentricity of the lens group arranged closest to the image. 
     In the zoom optical system ZL according to the third embodiment, the fourth lens group G 4  is configured to comprise an aperture stop S. With this arrangement, it is possible to suppress a fluctuation of astigmatism generated in the fourth lens group G 4 , therefore high optical performance can be realized. 
     In the zoom optical system ZL according to the third embodiment, it is preferable that the following conditional expression (15) is satisfied.
 
0.480&lt; f 3/ ft&lt; 4.000   (15)
 
     where, ft denotes a focal length of the zoom optical system ZL in a telephoto end state, and 
     f3 denotes a focal length of the third lens group G 3 . 
     The conditional expression (15) defines a range of an appropriate focal length of the third lens group G 3 . By satisfying the conditional expression (15), a fluctuation of astigmatism and spherical aberration upon zooming can be suppressed. 
     When a corresponding value of the conditional expression (15) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of astigmatism and spherical aberration generated in the third lens group G 3  upon zooming, therefore high optical performance can be realized. 
     In order to further ensure the advantageous effect of the third embodiment, it is preferable that the lower limit of the conditional expression (15) is set to 0.570. 
     When a corresponding value of the conditional expression (15) exceeds an upper limit, upon zooming, a fluctuation of astigmatism generated in the fourth lens group G 4  becomes excessive, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the third embodiment, it is preferable that the upper limit of a conditional expression (15) is set to 3.200. In order to further ensure the advantageous effect of the third embodiment, it is preferable that the upper limit of the conditional expression (15) is set to 2.400. 
     In the zoom optical system ZL according to the third embodiment, it is preferable that the following conditional expression (16) is satisfied.
 
0.470&lt; f 4/ ft&lt; 0.900   (16)
 
     where, ft denotes a focal length of the zoom optical system ZL in a telephoto end state, and 
     f4 denotes a focal length of the fourth lens group G 4 . 
     The conditional expression (16) defines a range of an appropriate focal length of the fourth lens group G 4 . By satisfying the conditional expression (16), a fluctuation of astigmatism and aspherical aberration upon zooming can be suppressed. 
     When a corresponding value of the conditional expression (16) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of astigmatism and spherical aberration generated in the fourth lens group G 4  upon zooming, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the third embodiment, it is preferable that the lower limit of the conditional expression (16) is set to 0.530. 
     When a corresponding value of the conditional expression (16) exceeds an upper limit, it is necessary to enlarge amount of movement of the fourth lens group G 4  to the image surface I upon zooming, in order to secure a predetermined zoom ratio. As a result, since a diameter of the axial flux of light passing through the fourth lens group G 4  greatly changes, a fluctuation of spherical aberration upon zooming becomes excessive, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the third embodiment, it is preferable to set the upper limit of the conditional expression (16) to 0.720. 
     In the zoom optical system ZL according to the third embodiment, it is preferable that the the lens group arranged closest to the image has positive refractive power. With this arrangement, magnification used in the lens group arranged closest to the image becomes less 100%, therefore a composite focal length of the lens group arranged closer to the object side than the lens group arranged closest to the image (for example, corresponding to the first lens group G 1  to the fourth lens group G 4  in  FIG. 1 ) can be relatively enlarged. As a result, it is possible to relatively suppress influence of decentering coma aberration, etc. due to decentering of lenses generated in the lens group arranged closer to the object than the lens group arranged closest to the image upon manufacture, therefore high optical performance can be realized. 
     In the zoom optical system ZL according to the third embodiment, it is preferable that the following conditional expression (17) is satisfied.
 
3.000&lt; fR/fw&lt; 9.500   (17)
 
     where, fw denotes a focal length of the zoom optical system ZL in a wide-angle end state, and 
     fR denotes a focal length of the lens group arranged closest to the image. 
     The conditional expression (17) defines an appropriate focal length of the lens group arranged closest to the image. By satisfying the conditional expression (17), a fluctuation of distortion and astigmatism upon zooming can be suppressed. 
     When a corresponding value of the conditional expression (17) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of distortion and astigmatism generated in the lens group arranged closest to the image upon zooming, and high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the third embodiment, it is preferable to set the lower limit of a conditional expression (17) to 4.200. 
     When a corresponding value of the conditional expression (17) exceeds an upper limit, it becomes difficult to correct a fluctuation of astigmatism generated in the lens group arranged closer to the object side than the lens group arranged closest to the image, therefore high optical performance cannot be corrected. 
     In order to further ensure the advantageous effect of the third embodiment, it is preferable that the upper limit of the conditional expression (17) is set to 7.600. 
     In the zoom optical system ZL according to the third embodiment, it is preferable that the following conditional expression (18) is satisfied.
 
0.730&lt;(− f 2)/ fw&lt; 1.800   (18)
 
     where, fw denotes a focal length of the zoom optical system ZL in a wide-angle end state, and 
     f2 denotes a focal length of the second lens group G 2 . 
     The conditional expression (18) defines a range of an appropriate focal length of the second lens group G 2 . By satisfying the conditional expression (18), a fluctuation of astigmatism and spherical aberration upon zooming can be suppressed. 
     When a corresponding value of the conditional expression (18) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of astigmatism and spherical aberration generated in the second lens group G 2  upon zooming, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the third embodiment, it is preferable that the lower limit of the conditional expression (18) is set to 0.900. In order to further ensure the advantageous effect of the third embodiment, it is preferable that the lower limit of the conditional expression (18) is set to 1.065. 
     When a corresponding value of the conditional expression (18) exceeds an upper limit, it is necessary to enlarge a change of a distance between the first lens group G 1  and the second lens group G 2  upon zooming, in order to secure a predetermined zoom ratio. As a result, since a ratio of a diameter of the axial flux of light passing through the first lens group G 1  and the second lens group G 2  greatly changes, a fluctuation of spherical aberration upon zooming becomes excessive, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the third embodiment, it is preferable that the upper limit of a conditional expression (18) is set to 1.600. 
     In the zoom optical system ZL according to the third embodiment, the following conditional expression (19) is satisfied.
 
−0.100&lt;( d 3 t−d 3 w )/ fw&lt; 0.330   (19)
 
     where, fw denotes a focal length of the zoom optical system ZL in a wide-angle end state, 
     d3w denotes a distance on the optical axis from the lens arranged closest to the image side of the third lens group G 3  in a wide-angle end state to the lens surface arranged closest to the object 
     side of the fourth lens group G 4 , and d3t denotes a distance on the optical axis from the lens surface arranged closest to the image side of the third lens group G 3  in a telephoto end state to the lens arranged closest to the object side of the fourth lens group G 4 . 
     The conditional expression (19) defines an appropriate range of a change of a distance between the third lens group G 3  and the fourth lens group G 4  upon zooming. By satisfying the conditional expression (19), a fluctuation of astigmatism upon zooming can be suppressed. 
     When a corresponding value of the conditional expression (19) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of astigmatism generated in the third lens group G 3  upon zooming, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the third embodiment, it is preferable that the lower limit of the conditional expression (19) is set to −0.080. 
     When a corresponding value of the conditional expression (19) exceeds an upper limit, a change a height from the optical axis of the off-axial flux of light passing through the fourth lens group G 4  becomes large upon zooming, therefore a fluctuation of astigmatism generated in the fourth lens group G 4  becomes excessive, thereby high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the third embodiment, it is preferable that the upper limit of the conditional expression (19) is set to 0.275. 
     In the zoom optical system ZL according to the third embodiment, it is preferable that the first lens group G 1  moves to the object side upon zooming from a wide-angle end state to a telephoto end state. With this arrangement, it is possible to suppress a change of a height on the optical axis of the off-axial flux of light passing through the first lens group G 1  upon zooming. As a result, it is possible to suppress a fluctuation of astigmatism generated in the first lens group G 1  upon zooming. 
     In the zoom optical system ZL according to the third embodiment, it is preferable that a distance between the first lens group G 1  and the second lens group G 2  increases upon zooming from a wide-angle end state to a telephoto end state. With this arrangement, since magnification of the second lens group G 2  can be doubled upon zooming from a wide-angle end state to a telephoto end state, a focal length of all lens groups can be configured to be long, therefore a fluctuation of astigmatism and spherical aberration upon zooming can be suppressed. 
     In the zoom optical system ZL according to the third embodiment, it is preferable that a distance between the second lens group G 2  and the third lens group G 3  decreases upon zooming from a wide-angle end state to a telephoto end state. With this arrangement, since a composite magnification from the third lens group G 3  to the fifth lens group G 5  upon zooming from a wide-angle end state to a telephoto end state, a focal length of all lens groups can be configured to be long, therefore a fluctuation of astigmatism and spherical aberration upon zooming can be suppressed. 
     In the zoom optical system ZL according to the third embodiment, it is preferable that an aperture stop S is disposed between the third lens group G 3  and the fourth lens group G 4 . With this arrangement, a change of a height from the optical axis of the off-axial flux of light passing through the third lens group G 3  and the fourth lens group G 4  upon zooming can be reduced, therefore a fluctuation of astigmatism generated in the third lens group G 3  and the fourth lens group G 4  can be suppressed, thereby high optical performance can be realized. 
     In the zoom optical system ZL according to the third embodiment, it is preferable that the third lens group G 3  moves along the optical axis upon focusing. With this arrangement, amount of movement upon focusing on a telephoto side is suppressed, and a fluctuation of a height from the optical axis regarding light incident on the third lens group G 3  which is a focusing lens group on the telephoto side is suppressed, therefore a fluctuation of astigmatism and spherical aberration upon focusing can be suppressed. 
     In the zoom optical system ZL according to the third embodiment, it is preferable that the third lens group G 3  moves to the image side upon focusing from an infinity object to a short-distance object. With this arrangement, focusing can be performed only with the third lens group G 3 , therefore a fluctuation of astigmatism and spherical aberration upon focusing can be suppressed, thereby high optical performance can be realized. 
     According to the zoom optical system ZL according to the third embodiment equipped with the above configurations, it is possible to realize the zoom optical system having high optical performance over the whole zoom range. 
     Next, referring to  FIG. 17 , a camera (optical device) equipped with the above zoom optical system ZL is described. This camera  1  has the same configurations as those of the first embodiment, and its configurations are already described, thus the explanations are omitted. 
     The zoom optical system ZL according to the third embodiment installed as the photographic lens  2  in the camera  1  has, as found in each example mentioned below, high optical performance over the whole zoom range with the characteristic lens configurations. Thus, according to the camera  1  according to the third embodiment, it is possible to realize an optical device having high optical performance over the whole zoom range. 
     Note that in case of installing the zoom optical system ZL mentioned above on a single lens reflex type camera having a quick return mirror and observing a photographic subject with a finder optical system, the same advantageous effect as the above camera  1  can be obtained. In case of installing the zoom optical system ZL on a video camera, the same advantageous effect as the camera  1  can be obtained. 
     Next, referring to  FIG. 20 , a method for manufacturing the zoom optical system ZL is outlined. Firstly, each lens is disposed in a lens-barrel so that a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group are arranged in order from an object (Step ST 310 ). In this situation, each lens is disposed so that a distance between the first lens group G 1  and the second lens group G 2  upon zooming, a distance between the second lens group G 2  and the third lens group G 3 G, a distance between the third lens group G 3  and the fourth lens group G 4 , and a distance between the fourth lens group G 4  and the fifth lens group G 5  change upon zooming (Step ST 320 ). Each lens is disposed so that the lens group arranged closest to the images approximately fixed to an image surface upon zooming (Step ST 330 ). The fourth lens group G 4  is configured to have an aperture stop S (Step ST 340 ). 
     Exampling a lens arrangement in the third embodiment, in the zoom optical system ZL illustrated in  FIG. 1 , as the first lens group G 1  having positive refractive power, a cemented lens composed of a negative meniscus lens L 11  having a convex surface facing an object and a biconvex positive lens L 12 , and a positive meniscus lens L 13  having a convex surface facing an object are disposed in the lens-barrel in order from an object along an optical axis. As the second lens group G 2  having negative refractive power, a negative meniscus lens L 21  having a convex surface facing the object, a biconcave negative lens L 22 , and a biconvex positive lens L 23  are disposed in the lens-barrel in order from the object along the optical axis. As the third lens group having positive refractive power, a biconvex positive lens L 31  is disposed in the lens-barrel. As the fourth lens group G 4  having positive refractive power, the aperture stop S, a cemented lens composed of a negative meniscus lens L 41  having a convex surface facing the object and a biconvex positive lens L 42 , a cemented lens composed of a biconvex positive lens L 43  and a negative meniscus lens L 44  having a concave surface facing to the object, and a negative meniscus lens L 45  having a convex surface facing the object are disposed in the lens-barrel. As the fifth lens group G 5 , a positive meniscus lens L 51  having a concave surface facing the object is disposed in the lens-barrel. 
     According to the method for manufacturing the zoom optical system according to the third embodiment, it is possible to manufacture the zoom optical system ZL having high optical performance over the whole zoom range. 
     As described above, according to the third embodiment, it is possible to solve a problem owned by the conventional zoom optical system such that it is difficult to maintain sufficiently high optical performance over the whole zoom range. 
     Next, the fourth embodiment is described with referred to drawings. The zoom optical system ZL according to the fourth embodiment is configured to comprise, as illustrated in  FIG. 1 , in order from an object along an optical axis, a first lens group G 1  having positive refractive power, a second lens group G 2  having negative refractive power, a third lens group G 3  having positive refractive power, a fourth lens group G 4  having positive refractive power, and a distance between the first lens group G 1  and the second lens group G 2 , a distance between the second lens group G 2  and the third lens group G 3 , and a distance between the third lens group G 3  and the fourth lens group G 4  are configured to change upon zooming. With this arrangement, it is possible to realize zooming, and suppress respective fluctuations of spherical aberration, astigmatism, and distortion accompanying zooming. 
     In the zoom optical system ZL according to the fourth embodiment, a fourth lens group G 4  comprises, in order from the object along the optical axis, a fourth A sublens group G 4 A (vibration-free lens group) configured to enable to move in a manner of having a component in a direction perpendicular to the optical axis in order to correct image blur, and a fourth B sublens group G 4 B. With this arrangement, a ratio of amount of movement regarding an image in the direction perpendicular to the optical axis against amount of movement of the fourth A sublens group G 4 A in the direction perpendicular to the optical axis can be appropriate, therefore astigmatism and decentering coma aberration generated while the fourth A sublens group G 4 A is moving can be suppressed. 
     In the zoom optical system ZL according to the fourth embodiment, it is preferable that a distance between the fourth A sublens group G 4 A and the fourth B sublens group G 4 B is constant. With this arrangement, tilt decentering between the fourth A sublens group G 4 A and the fourth B sublens group G 4 B when manufacturing can be suppressed, therefore astigmatism and decentering coma aberration due to the tilt decentering can be suppressed. 
     In the zoom optical system ZL according to the fourth embodiment, it is preferable that the following conditional expression (20) is satisfied.
 
0.480&lt; f 3/ ft&lt; 4.000   (20)
 
     where, ft denotes a focal length of the zoom optical system ZL in a telephoto end state, and 
     f3 denotes a focal length of the third lens group G 3 . 
     The conditional expression (20) defines a range of an appropriate focal length of the third lens group G 3 . By satisfying the conditional expression (20), it is possible to suppress a fluctuation of astigmatism and spherical aberration upon zooming, and astigmatism and decentering coma generated when the fourth A sublens group G 4 A is moving in the direction perpendicular to the optical axis. 
     When a corresponding value of the conditional expression (20) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of astigmatism and spherical aberration generated in the third lens group G 3  upon zooming, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the fourth embodiment, it is preferable that the lower limit of the conditional expression (20) is set to 0.570. 
     When a corresponding value of the conditional expression (20) exceeds an upper limit, a fluctuation of astigmatism generated in the fourth lens group G 4  becomes excessive upon zooming, thereby high optical performance cannot be realized. A ratio of amount of movement regarding the image in the direction perpendicular to the optical axis against amount of movement in the direction perpendicular to the optical axis regarding the fourth A sublens group G 4 A decreases, accordingly necessary amount of movement of the fourth A sublens group G 4 A in the direction perpendicular to the optical axis increases. Then, it becomes impossible to suppress astigmatism and decentering coma generated when the fourth A sublens group G 4 A is moving in the direction perpendicular to the optical axis 
     In order to further ensure the advantageous effect of the fourth embodiment, it is preferable that the upper limit of the conditional expression (20) is set to 3.200. In order to additionally ensure the advantageous effect of the fourth embodiment, it is preferable that the upper limit of the conditional expression (20) is set to 2.400. 
     In the zoom optical system ZL according to the fourth embodiment, it is preferable that the fourth A sublens group G 4 A has positive refractive power. With this arrangement, a ratio of amount of movement regarding the image in the direction perpendicular to the optical axis against amount of movement in the direction perpendicular to the optical axis of the fourth A sublens group G 4 A can be appropriate, thus astigmatism and decentering coma aberration generated while the fourth A sublens group G 4 A is moving can be suppressed. 
     In the zoom optical system ZL according to the fourth embodiment, it is preferable that the following conditional expression (21) is satisfied.
 
0.900&lt; f 4/ fw&lt; 4.450   (21)
 
     where, fw denotes a focal length of the zoom optical system ZL in a wide-angle end state, and 
     f4 denotes a focal length of the fourth lens group G 4 . 
     The conditional expression (21) defines a range of an appropriate focal length of the fourth lens group G 4 . By satisfying the conditional expression (21), a fluctuation of astigmatism and spherical aberration upon zooming can be suppressed. 
     When a corresponding value of the conditional expression (21) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of astigmatism and spherical aberration generated in the fourth lens group G 4  upon zooming, thereby high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the fourth embodiment, it is preferable that the lower limit of the conditional expression (21) is set to 1.400. In order to additionally ensure the advantageous effect of the fourth embodiment, it is preferable that the lower limit of the conditional expression (21) is set to 2.500. 
     When a corresponding value of the conditional expression (21) exceeds an upper limit, it is necessary to increase amount of movement regarding the fourth lens group G 4  against the image surface I, upon zooming, in order to secure a predetermined zoom ratio. As a result, since a diameter of the axial flux of light passing through the fourth lens group G 4  greatly changes, a fluctuation of spherical aberration upon zooming becomes excessive, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the fourth embodiment, it is preferable that the upper limit of the conditional expression (21) is set to 4.200. 
     In the zoom optical system ZL according to the fourth embodiment, it is preferable that the following conditional expression (22) is satisfied.
 
0.600&lt; f 3/ f 4&lt;4.000   (22)
 
     where, f3 denotes a focal length of the third lens group G 3 , and 
     f4 denotes a focal length of the fourth lens group G 4 . 
     The conditional expression (22) defines a range of an appropriate focal length of the third lens group G 3  and the fourth lens group G 4 . By satisfying the conditional expression (22), it is possible to suppress a fluctuation of astigmatism and spherical aberration upon zooming, and astigmatism and decentering coma aberration generated when the fourth A sublens group G 4 A is moving in the direction perpendicular to the optical axis. 
     When a corresponding value of the conditional expression (22) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of astigmatism and spherical aberration generated in the third lens group G 3  upon zooming, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the fourth embodiment, it is preferable that the lower limit of the conditional expression (22) is set to 0.840. In order to further ensure the advantageous effect of the fourth embodiment, it is preferable that the lower limit of the conditional expression (22) is set to 0.970. 
     When a corresponding value of the conditional expression (22) exceeds an upper limit, a ratio of amount of movement regarding the image in the direction perpendicular to the optical axis against amount of movement in the direction perpendicular to the optical axis of the fourth A sublens group G 4 A decreases, accordingly necessary amount of movement regarding the fourth A sublens group G 4 A in the direction perpendicular to the optical axis increases. Then, it is possible to suppress astigmatism and decentering coma aberration generated when the fourth A sublens group G 4 A moves in a direction perpendicular to the optical direction. 
     In order to further ensure the advantageous effect of the fourth embodiment, it is preferable that the upper limit of the conditional expression (22) is set to 2.880. 
     In the zoom optical system ZL according to the fourth embodiment, it is preferable that the following conditional expression (23) is satisfied.
 
0.155&lt;(− f 2)/ ft&lt; 0.500   (23)
 
     where, ft denotes a focal length of the zoom optical system ZL in a telephoto end state, and 
     f2 denotes a focal length of the second lens group G 2 . 
     The conditional expression (23) defines a range of an appropriate focal length of the second lens group G 2 . By satisfying the conditional expression (23), it is possible to suppress a fluctuation of astigmatism and spherical aberration upon zooming. 
     When a corresponding value of the conditional expression (23) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of astigmatism and spherical aberration generated in the second lens group G 2  upon zooming, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the fourth embodiment, it is preferable that the lower limit of the conditional expression (23) is set to 0.170. 
     When a corresponding value of the conditional expression (23) exceeds an upper limit, it is necessary to enlarge a change of a distance between the first lens group G 1  and the second lens group G 2  upon zooming in order to secure a predetermined zoom ratio. As a result, since a ratio of a diameter of the axial flux of light passing through the first lens group G 1  and the second lens group G 2  greatly changes, a fluctuation of spherical aberration upon zooming becomes excessive, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the fourth embodiment, it is preferable that the upper limit of the conditional expression (23) is set to 0.380. 
     In the zoom optical system ZL according to the fourth embodiment, it is preferable that the following conditional expression (24) is satisfied.
 
0.750&lt; f 1/ ft&lt; 3.000   (24)
 
     where, ft denotes a focal length of the zoom optical system ZL in a telephoto end state, and 
     f1 denotes a focal length of the first lens group G 1 . 
     The conditional expression (24) defines a range of an appropriate focal length of the first lens group G 1 . By satisfying the conditional expression (24), it is possible to suppress a fluctuation of astigmatism and spherical aberration upon zooming. 
     When a corresponding value of the conditional expression (24) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of chromatic aberration of magnification, astigmatism, and spherical aberration generated in the first lens group G 1  upon zooming, therefore high optical performance is not realized. 
     In order to further ensure the advantageous effect of the fourth embodiment, it is preferable that the lower limit of the conditional expression (24) is set to 0.850. 
     When a corresponding value of the conditional expression (24) exceeds an upper limit, it is necessary to increase a change of a distance between the first lens group G 1  and the second lens group G 2  upon zooming in order to secure a predetermined zoom ratio. As a result, since a height from the optical axis of the off-axial flux of light passing through the first lens group G 1  greatly changes, a fluctuation of astigmatism upon zooming becomes excessive, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the fourth embodiment, it is preferable that the upper limit of the conditional expression (24) is set to 2.000. In order to additionally ensure the advantageous effect of the fourth embodiment, it is preferable that the upper limit of the conditional expression (24) is set to 1.700. 
     It is preferable that the zoom optical system ZL according to the fourth embodiment comprise the fifth lens group G 5  on an image side of the fourth lens group G 4  along the optical axis, and a distance between the fourth lens group G 4  and the fifth lens group G 5  changes upon zooming. With this arrangement, since zooming can be efficiently performed, refractive power of the fourth lens group G 4  can be weakened, therefore it is possible to suppress a fluctuation of spherical aberration, astigmatism and distortion accompanying zooming and generated in the fourth lens group G 4 . 
     In the zoom optical system ZL according to the fourth embodiment, it is preferable that the lens group arranged closest to the image (for example, corresponding to the fifth lens group G 5  in  FIG. 1 ) is approximately fixed against the image surface I. By approximately fixing the lens group arranged closest to the image against the image surface I mentioned above, a change of a height of the off-axial flux of light passing through the lens group arranged closest to the image can be optimized, therefore a fluctuation of astigmatism and distortion can be suppressed. This enables to simplify a lens-barrel structure configuring the zoom optical system ZL, suppress decentering due to manufacturing errors, etc., and suppress inclination of surrounding image surfaces and decentering coma aberration generated due to decentering of the lens group arranged closest to the image. 
     In the zoom optical system ZL according to the fourth embodiment, it is preferable that the lens group arranged closest to the image has positive refractive power. With this arrangement, magnification used in the lens arranged closest to the image becomes less than 100%, therefore it is possible to relatively increase a composite focal length of the lens group arranged closer to the object (for example, corresponding to the first lens group G 1  to the fourth lens group G 4  in  FIG. 1 ) than the lens group arranged closest to the image. As a result, it is possible to relatively suppress influence of decentering coma aberration generated due to decentering between lenses, generated in the lens arranged closer to the object than the lens group arranged closest to the image when manufacturing, therefore high optical performance can be realized. 
     In the zoom optical system ZL according to the fourth embodiment, it is preferable that the following conditional expression (25) is satisfied.
 
3.000&lt; fR/fw&lt; 9.500   (25)
 
     where, fw denotes a focal length of the zoom optical system ZL in a wide-angle end state, and 
     fR denotes a focal length of the lens group arranged closest to the image. 
     The conditional expression (25) defines a range of an appropriate focal length of the lens group arranged closest to the image. By satisfying the conditional expression (25), it is possible to suppress a fluctuation of distortion and astigmatism upon zooming. 
     When a corresponding value of the conditional expression (25) becomes less than a lower limit, it becomes difficult to suppress a fluctuation of distortion and astigmatism generated in the lens group arranged closest to the image upon zooming, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the fourth embodiment, it is preferable that the lower limit of the conditional expression (25) is set to 4.200. 
     When a corresponding value of the conditional expression (25) exceeds an upper limit, it becomes difficult to correct a fluctuation of astigmatism generated in the lens group arranged closer to the object than the lens group arranged closest to the image by the lens group arranged closest to the image, therefore high optical performance cannot be realized. 
     In order to further ensure the advantageous effect of the fourth embodiment, it is preferable that the upper limit of the conditional expression (25) is set to 7.600. 
     In the zoom optical system ZL according to the fourth embodiment, it is preferable that only the third lens group G 3  moves along the optical axis upon focusing. With this arrangement, amount of movement upon focusing on a telephoto side is suppressed, and a fluctuation of a height from the optical axis regarding light incident on the third lens group G 3  which is a focusing lens group in the telephoto side can be suppressed, therefore a fluctuation of astigmatism and spherical aberration upon focusing can be suppressed. 
     In the zoom optical system ZL according to the fourth embodiment, it is preferable that the third lens group G 3  moves to the image side upon focusing from an infinity object to a short-distance object. With this arrangement, it becomes possible to focus only with the third lens group G 3 , it is possible to suppress a fluctuation of astigmatism and spherical aberration upon focusing while downsizing the focusing lens group, therefore high optical performance can be realized. 
     In the zoom optical system ZL according to the fourth embodiment, it is preferable that the first lens group G 1  moves to the object side upon zooming from a wide-angle end state to a telephoto end state. With this arrangement, it is possible to suppress a change of a height from the optical axis regarding an off-axial flux of light passing through the first lens group G 1  upon zooming. With this arrangement, it is possible to suppress a fluctuation of astigmatism upon zooming generated by the first lens group G 1 . 
     In the zoom optical system ZL according to the fourth embodiment, it is preferable that a distance between the first lens group G 1  and the second lens group G 2  increases upon zooming from a wide-angle end state to a telephoto end state. With this arrangement, since magnification of the second lens group G 2  can be doubled upon zooming from the wide-angle end state to the telephoto end state, a focal length of all lens groups can be configured to be long, therefore a fluctuation of astigmatism and spherical aberration upon zooming can be suppressed. 
     In the zoom optical system ZL according to the fourth embodiment, it is preferable that a distance between the second lens group G 2  and the third lens group G 3  decreases upon zooming from a wide-angle end state to a telephoto end state. With this arrangement, since a composite magnification regarding from the third lens group to the lens group arranged closest to the image can increase upon zooming from the wide-angle end state to the telephoto end state, a focal length of all lens groups can be configured to be long, therefore a fluctuation of astigmatism and spherical aberration upon zooming can be suppressed. 
     In the zoom optical system ZL according to the fourth embodiment, it is preferable that the fourth lens group G 4  has an aperture stop S. With this arrangement, a fluctuation of astigmatism generated in the fourth lens group G 4  can be suppressed upon zooming, therefore high optical performance can be realized. 
     In the zoom optical system ZL according to the fourth embodiment, it is preferable that the aperture stop S is disposed between the third lens group G 3  and the fourth lens group G 4 . With this arrangement, a change of a height from the optical axis regarding an off-axial flux of light passing through the third lens group G 3  and the fourth lens group G 4  upon zooming can be reduced, and a fluctuation of astigmatism generated in the third lens group G 3  and the fourth lens group G 4  can be suppressed, therefore high optical performance can be realized. 
     According to the zoom optical system ZL according to the fourth embodiment equipped with the above configurations, it is possible to realize the zoom optical system not only having high optical performance over a whole zoom range, but also having high optical performance high when correcting image blur. 
     Next, referring to  FIG. 17 , a camera (optical device) equipped with the zoom optical system ZL is described. This camera  1  has the same configurations as those of the first embodiment, and its configurations have already been described, the explanation is omitted here. 
     As found in each example mentioned below, the zoom optical system ZL according to the fourth embodiment equipped on the camera  1  as the photographing lens  2  has not only high optical performance over the whole zoom range, by the characteristic lens configurations, but also have high optical performance when correcting image blur. Therefore, according to the camera  1  according to the fourth embodiment, it is possible to realize an optical device not only having high optical performance over the whole zoom range, but also having high optical performance when correcting image blur. 
     Note that in case of installing the zoom optical system ZL mentioned above on a single lens reflex type camera having a quick return mirror and observing a photographic subject with a finder optical system, the same advantageous effect as the above camera  1  can be obtained. In case of installing the zoom optical system ZL on a video camera, the same advantageous effect as the camera  1  can be obtained. 
     Next, referring to  FIG. 21 , a method for manufacturing the zoom optical system ZL is outlined. Firstly, each lens is disposed in a lens-barrel so that a first lens group G 1  having positive refractive power, a second lens group G 2  having negative refractive power, a third lens group having positive refractive power, and a fourth lens group G 4  having positive refractive power are arranged in order from an object (Step ST 410 ). At this point, each lens is disposed so that a distance between the first lens group G 1  and the second lens group G 2 , a distance between the second lens group G 2  and the third lens group G 3 , and a distance between the third lens group G 3  and the fourth lens group G 4  change upon zooming (Step ST 420 ). Each lens is disposed so that the fourth lens group G 4  comprises, in order from an object, a fourth A sublens group G 4 A configured to enable to move in a manner of having a component in a direction perpendicular to the optical axis in order to correct image blur, and a fourth B sublens group G 4 B (Step ST 430 ). 
     Exampling a lens arrangement according to the fourth embodiment, the zoom optical system ZL illustrated in  FIG. 1 , as the first lens group G 1  having positive refractive power, a cemented lens composed of a negative meniscus lens L 11  having a convex surface facing the object and a biconvex positive lens L 12 , and a positive meniscus lens L 13  having a convex surface facing the object are disposed in the lens-barrel. As the second lens group G 2  having negative refractive power, a negative meniscus lens L 21  having a convex surface facing the object, a biconcave negative lens L 22 , and a biconvex positive lens L 23  are disposed in the lens-barrel. As the third lens group G 3  having positive refractive power, a biconvex positive lens L 31  is disposed in the lens-barrel. As the fourth lens group G 4  having positive refractive power, a fourth A sublens group G 4 A configured of a cemented lens composed of a negative meniscus lens L 41  having a convex surface facing the object and a biconvex positive lens L 42 , a fourth B lens group G 4 B composed of a cemented lens composed of a biconvex positive lens L 43  and a negative meniscus lens L 44  having a concave surface facing the object, and a negative meniscus lens L 45  having a convex surface facing the object are disposed in the lens-barrel in order from the object along the optical axis. As the fifth lens group G 5 , a positive meniscus lens L 51  having a concave surface facing the object is disposed in the lens-barrel. 
     According to the method for manufacturing the zoom optical system according to the fourth embodiment, it is possible to manufacture the zoom optical system ZL not only having high optical performance over the whole zoom range, but also having high optical performance when correcting image blur. 
     As described above, according to the fourth embodiment, it is possible to solve a problem such that it is difficult to maintain sufficiently-high optical performance over the whole zoom range, and a problem such that it is difficult to obtain sufficiently-high optical performance when correcting image blur, owned by a conventional zoom optical system. 
     Examples According to First to Fourth Embodiments 
     Each example according to the first to fourth embodiments is described based on drawings. Tables 1 to 4 are now shown, and these are Tables of each various data according to Example 1 to Example 4. 
     However, Example 4 corresponds only to the fourth embodiment. 
     Each reference sign regarding  FIG. 1  according to Example 1 is used independently for every example, in order to avoid complicating explanations due to swelling of the digit number of reference signs. Therefore, even if attached with the same reference signs as those in drawings according to other examples, this does not necessarily mean the same configurations as those in the other examples. 
     In each example, d-line (wave length of 587.5620 nm) and g-line (wave length of 435.8350 nm) are selected as subjects for calculating aberration characteristics. 
     In the [Lens data] in tables, a surface number means an order of each optical surface from the object side along a direction light travels, R means a radius of curvature of each optical surface, D means a surface distance on the optical axis from each optical surface to the next optical surface (or image surface), nd means a refractive index against d-line of a material of a optical member, and vd means an Abbe number on the basis of d-line of a material of the light member. Object surface means an object surface, (Variable) means a variable distance between surfaces, “∞” of a radius of curvature means a plane or an aperture, (Stop S) means an aperture stop S, and an image surface means an image surface I. The refractive index “1.000000” of air is omitted. In a case the optical surface is an aspherical surface, a sign “*” is assigned to the surface number and a paraxial radius of curvature is shown in a column of a radius of curvature R. 
     In [Aspherical surface data] in tables, regarding the aspherical surfaces in the [Lens data], the configuration is defined by the following expression (a). X(y) means a distance along the optical axis direction from a tangent plane in a vertex of the aspherical surface to a position on the aspherical surface in height y, and R means a radius of curvature (paraxial radius of curvature) of a criterion spherical surface, κ means a conic constant, and, Ai means an i-th aspherical surface coefficient. “E−n” means “×10 −n .” For example, 1.234E−05=1.234×10 −5 . Note that the secondary aspherical surface coefficient A2 is 0, and its description is omitted.
 
 x ( y )=( y   2   /R )/{1+(1− k   ×y   2   /R   2 ) 1/2   }+A 4 y   4   +A 6 y   6   +A 8 y   8   +A 10 y   10   +A 12 y   12    (a)
 
     In [Various data] in Tables, f means a focal length of a lens whole system, and FNo means a F number, ω means an half-angle of view (units: degree), Y means an image height, φ means the diameter of the aperture stop S, TL means a total optical length of a lens (a distance on the optical axis from a first surface upon focusing on an infinity object to the image surface I), and BF means backfocus (a distance on the optical axis from the lens surface arranged closest to the image surface upon focusing on the infinity object to the image surface I). W means a wide-angle end state, M means an intermediate focal length state, and T means a telephoto end state. 
     In [Variable distance data] in Tables, a value Di of a variable distance in each state of a wide-angle end state upon focusing on infinity (W), an intermediate focal length state (M), and a telephoto end state (T) are shown. Note that Di means a variable distance between an i-th surface and an (i+1)-th surface. 
     In [Amount of movement of focusing group upon focusing] in Tables, amount of movement of a focusing lens group (the third lens group G 3 ) from an infinity focusing state to a short-distance focusing state (distance between object images: 1.00 m) is shown. Here, regarding a moving direction of the focusing lens group, moving to the image side is defined as positive. An shooting distance means a distance from the object to the image surface I. 
     In [lens group data] in Tables, a frontend surface and a focal length regarding each lens group are shown. 
     In [Values corresponding to the conditional expressions] in Tables, values corresponding to the above conditional expressions are shown. 
     Hereinafter, in all general data values, regarding the focal length f, a radius of curvature R, a distance D, and other lengths, etc. as shown, “mm” is generally used except a specific request, however an optical system is not limited to the above, since equivalent optical performance can be obtained even if the optical system is proportionally enlarged or proportionally shrinked. Moreover, the unit is not limited to “mm, ” another appropriate unit is available, instead. 
     The explanations concerning the tables are common among all the examples, thus hereinafter the explanation is omitted. 
     EXAMPLE 1 
     Example 1 is described using  FIG. 1 ,  FIGS. 2A, 2B and 2C ,  FIGS. 3A, 3B and 3C , FIGS. 4 A,  4 B and  4 C and Table 1. The zoom optical system ZL (ZL 1 ) according to Example 1 comprises, as illustrated in  FIG. 1 , in order from an object along an optical axis, a first lens group G 1  having positive refractive power, a second lens group G 2  having negative refractive power, a third lens group G 3  having positive refractive power, a fourth lens group G 4  having positive refractive power, and a fifth lens group G 5  having positive refractive power. An aperture stop S is provided between the third lens group G 3  and the fourth lens group G 4 , and the aperture stop S configures the fourth lens group G 4 . The fifth lens group G 5  is the lens group arranged closest to the image. 
     The first lens group G 1  is composed of, in order from the object along the optical axis, a cemented lens composed of a negative meniscus lens L 11  having a convex surface facing the object and a biconvex positive lens L 12 , and a positive meniscus lens L 13  having a convex surface facing the object. 
     The second lens group G 2  is composed of, in order from the object along the optical axis, a negative meniscus lens L 21  having a convex surface facing the object, a biconcave negative meniscus lens L 22 , and a biconvex positive lens L 23 . Note that the negative meniscus lens L 21  is a complexed aspherical lens made from resin and glass, in which a lens surface on the object side is aspherical shaped. 
     The third lens group G 3  is composed of a biconvex positive lens L 31 . Note that the positive lens L 31  is a glass-molded aspherical lens, in which lens surfaces on the object and image sides are aspherical shaped. 
     The fourth lens group G 4  is composed of, in order from the object along the optical axis, a fourth A sublens group G 4 A configured of a cemented lens composed of a negative meniscus lens L 41  having a convex surface facing the object and a biconvex positive lens L 42 , a fourth B sublens group G 4 B configured of a cemented lens composed of a biconvex positive lens L 43  and a negative meniscus lens L 44  having a concave surface facing the object, and a negative meniscus lens L 45  having a convex surface facing the object. Note that the negative meniscus lens L 44  is a glass-molded aspherical lens in which a lens surface on the image side is aspherical shaped. 
     The fifth lens group G 5  is composed of a positive meniscus lens L 51  having a concave surface facing the object. 
     In the zoom optical system ZL 1  according to the present example, the first lens group G 1  to the fourth lens group G 4  moves along the optical axis so that an air distance between the first lens group G 1  and the second lens group G 2 , an air distance between the second lens group G 2  and the third lens group G 3 , an air distance between the third lens group G 3  and the fourth lens group G 4 , and an air distance between the fourth lens group G 4  and the fifth lens group G 5  respectively change upon focusing from a wide-angle end state to a telephoto end state. The fifth lens group G 5  is fixed to the image surface I. 
     Specifically speaking, the first lens group G 1  to the fourth lens group G 4  move to the object side. The aperture stop S moves to the object side together with the fourth lens group G 4 . 
     With this arrangement, upon zooming, the air distance between the first lens group G 1  and the second lens group G 2  increases, the air distance between the second lens group G 2  and the third lens group decreases, the air distance between the third lens group G 3  and the fourth lens group G 4  increases, and the air distance between the fourth lens group G 4  and the fifth lens group G 5  increase. The air distance between the aperture stop S and the third lens group G 3  increases. 
     Focusing is performed by moving the third lens group G 3  along the optical axis. Specifically speaking, this is performed by moving the third lens group G 3  to the image side along the optical axis upon focusing from an infinity object to a short-distance object. 
     When image blur is generated, image blur on the image surface I is corrected (vibration-controlled) by moving the fourth A sublens group G 4 A as a vibration-free lens group in a manner of having a component in a direction perpendicular to the optical axis. 
     Table 1 shows values of each various data in Example 1. Surface numbers 1 to 25 in Table 1 correspond to each optical surface of m1 to m25 illustrated in  FIG. 1 . 
     
       
         
           
               
             
               
                 TABLE 1 
               
               
                   
               
             
            
               
                 [Lens Data] 
               
            
           
           
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
               
               
                 number 
                 R 
                 D 
                 nd 
                 νd 
               
               
                   
               
               
                 Object 
                 ∞ 
                   
                   
                   
               
               
                 surface 
                   
                   
                   
                   
               
               
                 1 
                 132.7211 
                 1.6000 
                 1.846660 
                 23.80 
               
               
                 2 
                 54.2419 
                 4.5271 
                 1.589130 
                 61.22 
               
               
                 3 
                 −1401.4921 
                 0.1000 
                   
                   
               
               
                 4 
                 36.9475 
                 4.0173 
                 1.696800 
                 55.52 
               
               
                 5 
                 200.3945 
                 D5 (Variable) 
                   
                   
               
               
                 *6 
                 510.0000 
                 0.0800 
                 1.560930 
                 36.64 
               
               
                 7 
                 288.8364 
                 1.0000 
                 1.816000 
                 46.59 
               
               
                 8 
                 8.8676 
                 4.8531 
                   
                   
               
               
                 9 
                 −23.6529 
                 0.9000 
                 1.696800 
                 55.52 
               
               
                 10 
                 37.1909 
                 0.7644 
                   
                   
               
               
                 11 
                 21.6553 
                 2.6218 
                 1.808090 
                 22.74 
               
               
                 12 
                 −149.6082 
                 D12 (Variable) 
                   
                   
               
               
                 *13 
                 31.4469 
                 1.4931 
                 1.589130 
                 61.15 
               
               
                 *14 
                 −454.8143 
                 D14 (Variable) 
                   
                   
               
               
                 15 
                 ∞ 
                 1.7118 
                 (Stop) 
                   
               
               
                 16 
                 17.8093 
                 0.9000 
                 1.834000 
                 37.18 
               
               
                 17 
                 10.8731 
                 2.4554 
                 1.497820 
                 82.57 
               
               
                 18 
                 −36.9740 
                 1.5005 
                   
                   
               
               
                 19 
                 14.0517 
                 2.3992 
                 1.518230 
                 58.82 
               
               
                 20 
                 −15.0205 
                 1.0034 
                 1.851350 
                 40.13 
               
               
                 *21 
                 −25.0875 
                 0.2985 
                   
                   
               
               
                 22 
                 23.6629 
                 2.4328 
                 1.902650 
                 35.73 
               
               
                 23 
                 8.6520 
                 D23 (Variable) 
                   
                   
               
               
                 24 
                 −29.8985 
                 2.0872 
                 1.617720 
                 49.81 
               
               
                 25 
                 −17.6129 
                 BF 
                   
                   
               
               
                 Image 
                 ∞ 
                   
                   
                   
               
               
                 surface 
               
               
                   
               
            
           
           
               
            
               
                 [Aspherical surface data] 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 The 6th surface 
               
               
                   
                 κ = 1.00000 
               
               
                   
                 A4 = 1.30134E−05 
               
               
                   
                 A6 = 5.20059E−08 
               
               
                   
                 A8 = −1.38176E−09 
               
               
                   
                 A10 = 6.06866E−12 
               
               
                   
                 A12 = 0.00000E+00 
               
               
                   
                 The 13th surface 
               
               
                   
                 κ = 0.3322 
               
               
                   
                 A4 = 5.55970E−05 
               
               
                   
                 A6 = 3.96498E−07 
               
               
                   
                 A8 = 3.97804E−09 
               
               
                   
                 A10 = 0.00000E+00 
               
               
                   
                 A12 = 0.00000E+00 
               
               
                   
                 The 14th surface 
               
               
                   
                 κ = 4.0000 
               
               
                   
                 A4 = 9.44678E−05 
               
               
                   
                 A6 = 5.47705E−07 
               
               
                   
                 A8 = 1.37698E−23 
               
               
                   
                 A10 = 0.00000E+00 
               
               
                   
                 A12 = 0.00000E+00 
               
               
                   
                 The 21th surface 
               
               
                   
                 κ = −1.0412 
               
               
                   
                 A4 = 8.07840E−06 
               
               
                   
                 A6 = −1.60525E−07 
               
               
                   
                 A8 = −3.84486E−09 
               
               
                   
                 A10 = 0.00000E+00 
               
               
                   
                 A12 = 0.00000E+00 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 W 
                 M 
                 T 
               
               
                   
               
            
           
           
               
            
               
                 [Various data] 
               
               
                 Zoom ratio 4.71 
               
            
           
           
               
               
               
               
               
            
               
                   
                 f 
                 10.29845 
                 32.00216 
                 48.49978 
               
               
                   
                 FNO 
                 3.60 
                 5.06 
                 5.79 
               
               
                   
                 ω 
                 39.76047 
                 13.63173 
                 9.16599 
               
               
                   
                 Y 
                 8.00 
                 8.00 
                 8.00 
               
               
                   
                 φ 
                 7.80 
                 8.30 
                 8.30 
               
               
                   
                 TL 
                 79.34243 
                 95.80944 
                 105.57918 
               
               
                   
                 BF 
                 13.25602 
                 13.25602 
                 13.25602 
               
            
           
           
               
            
               
                 [Variable distance data] 
               
            
           
           
               
               
               
               
               
            
               
                   
                 f 
                 10.29845 
                 32.00216 
                 48.49978 
               
               
                   
                 D5 
                 1.80000 
                 16.93666 
                 22.35926 
               
               
                   
                 D12 
                 18.49692 
                 5.54052 
                 1.80069 
               
               
                   
                 D14 
                 3.61695 
                 3.90524 
                 5.82908 
               
               
                   
                 D23 
                 5.42688 
                 19.42534 
                 25.58847 
               
            
           
           
               
            
               
                 [Amount of movement of focusing group upon focusing] 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Distance between 
                 1.00 m 
                 1.00 m 
                 1.00 m 
               
               
                   
                 object and image 
                   
                   
                   
               
               
                   
                 Amount of movement 
                 0.2652 
                 0.7481 
                 1.2334 
               
               
                   
               
            
           
           
               
            
               
                 [Lens group data] 
               
            
           
           
               
               
               
            
               
                 Group 
                 Group first 
                 Group focal 
               
               
                 number 
                 surface 
                 length 
               
               
                   
               
               
                 G1 
                 1 
                 57.25524 
               
               
                 G2 
                 6 
                 −11.09964 
               
               
                 G3 
                 13 
                 49.98341 
               
               
                 G4 
                 15 
                 28.96589 
               
               
                 G5 
                 24 
                 65.16201 
               
               
                   
               
            
           
           
               
            
               
                 [Values corresponding to conditional expressions] 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 Conditional expression(1)f3/ft = 1.031 
               
               
                   
                 Conditional expression(2)(−f2)/fw = 1.078 
               
               
                   
                 Conditional expression(3)f3/f4 = 1.726 
               
               
                   
                 Conditional expression(4)ν3 = 61.15 
               
               
                   
                 Conditional expression(5)(d3t − d3w)/fw = 0.215 
               
               
                   
                 Conditional expression(6)f4/ft = 0.597 
               
               
                   
                 Conditional expression(7)fR/fw = 6.326 
               
               
                   
                 Conditional expression(8)f3/ft = 1.031 
               
               
                   
                 Conditional expression(9)(d3t − d3w)/fw = 0.215 
               
               
                   
                 Conditional expression(10)fR/fw = 6.326 
               
               
                   
                 Conditional expression(11)(−f2)/fw = 1.078 
               
               
                   
                 Conditional expression(12)f4/ft = 0.597 
               
               
                   
                 Conditional expression(13)(d1t − d1w)/ft = 0.424 
               
               
                   
                 Conditional expression(14)(d2w − d2t)/ft = 0.344 
               
               
                   
                 Conditional expression(15)f3/ft = 1.031 
               
               
                   
                 Conditional expression(16)f4/ft = 0.597 
               
               
                   
                 Conditional expression(17)fR/fw = 6.326 
               
               
                   
                 Conditional expression(18)(−f2)/fw = 1.078 
               
               
                   
                 Conditional expression(19)(d3t − d3w)/fw = 0.215 
               
               
                   
                 Conditional expression(20)f3/ft = 1.031 
               
               
                   
                 Conditional expression(21)f4/fw = 2.812 
               
               
                   
                 Conditional expression(22)f3/f4 = 1.726 
               
               
                   
                 Conditional expression(23)(−f2)/ft = 0.229 
               
               
                   
                 Conditional expression(24)f1/ft = 1.180 
               
               
                   
                 Conditional expression(25)fR/fw = 6.326 
               
               
                   
               
            
           
         
       
     
     Based on Table 1, it is found that in the zoom optical system ZL 1  according to the present example, the conditional expressions (1) to (25) are satisfied. 
       FIGS. 2A, 2B, and 2C  illustrate graphs showing various aberrations (spherical aberration, astigmatism, distortion, coma aberration, and lateral chromatic aberration) upon focusing on infinity regarding the zoom optical system ZL 1  according to Example 1, where  FIG. 2A  depicts a wide-angle end state,  FIG. 2B  depicts an intermediate focal length state, and  FIG. 2C  depicts a telephoto end state.  FIGS. 3A, 3B, and 3C  illustrate graphs showing various aberrations (spherical aberration, astigmatism, distortion, coma aberration, and lateral chromatic aberration) upon focusing on a short-distance object (1.00 m of a distance between the object and image) regarding the zoom optical system ZL 1  according to Example 1, where  FIG. 3A  depicts a wide-angle end state,  FIG. 3B  depicts an intermediate focal length state, and  FIG. 3C  depicts a telephoto end state.  FIGS. 4A, 4B, and 4C  illustrate graphs showing meridional lateral aberration when correcting image blur upon focusing on infinity regarding the zoom optical system ZL 1  according to Example 1 (shift amount of a vibration-free lens group=0.1 mm), where  FIG. 4A  depicts a wide-angle end state,  FIG. 4B  depicts an intermediate focal length state, and  FIG. 4C  depicts a telephoto end state. In the present example, optical performance when controlling vibration, as illustrated in  FIGS. 4A, 4B and 4C , is illustrated in a meridional lateral aberration diagram corresponding to a screen center and an image height ±5.6 mm of an image height. 
     In each graph showing aberrations,  FNO  means a F number, and NA means the number of an aperture of light emitted from the lens arranged closest to the image, A means an angle of incidence of light, that is, a half angle of view (units: degree),  H 0 means the height of the object (units: mm), and  Y  means an image height. d means d-line, and g means g-line. What is not described with d or g means an aberration according to d-line. In graphs showing spherical aberration, a solid line indicates spherical aberration. In graphs showing astigmatism, a solid line indicates a sagittal image surface and a dashed-line shows a meridional image surface. In graphs showing coma aberration, a solid line indicates coma aberration in a meridional direction. Note that also in graphs showing aberrations of each example described below, the same signs are used as those in the present example. 
     As obvious based on each graph showing aberrations illustrated in  FIGS. 2A, 2B and 2C ,  FIGS. 3A, 3B and 3C , and  FIGS. 4A, 4B and 4C , in the zoom optical system ZL 1  according to Example 1, various aberrations are appropriately corrected covering a range of from a wide-angle end state to a telephoto end state, therefore high optical performance can be obtained. It is found that high image-forming performance can be obtained upon correcting image blur. 
     EXAMPLE 2 
     Example 2 is described using  FIG. 5 ,  FIGS. 6A, 6B and 6C ,  FIGS. 7A, 7B and 7C ,  FIGS. 8A, 8B and 8C  and Table 2. The zoom optical system ZL (ZL 2 ) according to Example 2 comprises, as illustrated in  FIG. 5 , in order from an object along an optical axis, a first lens group G 1  having positive refractive power, a second lens group G 2  having negative refractive power, a third lens group G 3  having positive refractive power, a fourth lens group G 4  having positive refractive power, and a fifth lens group G 5  having positive refractive power. An aperture stop S is provided between the third lens group G 3  and the fourth lens group G 4 , and the aperture stop S configures the fourth lens group G 4 . The fifth lens group G 5  is the lens group arranged closest to the image. 
     The first lens group G 1  is composed of, in order from the object along the optical axis, a cemented lens composed of a negative meniscus lens L 11  having a convex surface facing the object and a biconvex positive lens L 12 , and a positive meniscus lens L 13  having a convex surface facing the object. 
     The second lens group G 2  is composed of, in order from the object along the optical axis, a negative meniscus lens L 21  having a convex surface facing the object, a negative meniscus lens L 22  having a concave surface facing the object, and a biconvex positive lens L 23 . Note that the negative meniscus lens L 21  is a complexed aspherical lens made from resin and glass, in which a lens surface on the object side is aspherical-shaped. 
     The third lens group G 3  is composed of a positive meniscus lens L 31  having a convex surface facing the object. Note that the positive meniscus lens L 31  is a glass-molded aspherical lens in which a lens surface on the object side is aspherical-shaped. 
     The fourth lens group G 4  is composed of, in order from the object along the optical axis, a fourth A sublens group G 4 A configured of a cemented lens composed of a negative meniscus lens L 41  having a convex surface facing the object and a biconvex positive lens L 42 , a cemented lens composed of a biconvex positive lens L 43  and a negative meniscus lens L 44  having a concave surface facing the object, and a fourth B sublens group G 4 B configured of a cemented lens composed of a negative meniscus lens L 45  having a convex surface facing the object and a positive meniscus lens L 46  having a convex surface facing the object. Note that the negative meniscus lens L 44  is a glass-molded aspherical lens, in which a lens surface on the image side is aspherical-shaped. 
     The fifth lens group G 5  is composed of a positive meniscus lens L 51  having a concave surface facing the object. 
     In the zoom optical system ZL 2  according to the present embodiment, the first lens group G 1  to the fourth lens group G 4  move along the optical axis so that an air distance between the first lens group G 1  and the second lens group G 2 , an air distance between the second lens group G 2  and the third lens group G 3 , an air distance between the third lens group G 3  and the fourth lens group G 4 , and an air distance between the fourth lens group G 4  and the fifth lens group G 5  respectively change upon zooming. The fifth lens group G 5  is fixed to the image surface I. 
     Specifically speaking, the first lens group G 1 , the third lens group G 3 , and the fourth lens group G 4  move to the object side upon zooming from a wide-angle end state to a telephoto end state. The second lens group G 2  moves to the image side from a wide-angle end state to an intermediate focal length state, and moves to the object side from the intermediate focal length state to a telephoto end state. The aperture stop S moves to the object side together with the fourth lens group G 4 . 
     With this arrangement, upon zooming, the air distance between the first lens group G 1  and the second lens group G 2  increases, the air distance between the second lens group G 2  and the third lens group decreases, the air distance between the third lens group G 3  and the fourth lens group G 4  decreases from a wide-angle end state to an intermediate focal length state and increases from the intermediate focal length state to a telephoto end state, and the air distance between the fourth lens group G 4  and the fifth lens group G 5  increases. An air distance between the aperture stop S and the third lens group G 3  decreases from a wide-angle end state to an intermediate focal length state, and increases from the intermediate focal length state to a telephoto end state. 
     Focusing is performed by moving the third lens group G 3  along the optical axis. Specifically speaking, the third lens group G 3  is moved to the image side along the optical axis upon focusing from an infinity object to a short-distance object. 
     When image blur is generated, a correction of image blur (vibration-control) on the image surface I is performed by moving the fourth A sublens group G 4 A as a vibration-controlled lens group in a manner of having a component in a direction perpendicular to the optical axis. 
     Table 2illustrates values of each various data in Example 2. Surface numbers 1 to 26 in Table 2 correspond to each optical surface of m1 to m26 illustrated in  FIG. 5 . 
     
       
         
           
               
             
               
                 TABLE 2 
               
               
                   
               
             
            
               
                 [Lens Data] 
               
            
           
           
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
               
               
                 number 
                 R 
                 D 
                 nd 
                 νd 
               
               
                   
               
               
                 Object 
                 ∞ 
                   
                   
                   
               
               
                 surface 
                   
                   
                   
                   
               
               
                 1 
                 144.9435 
                 1.6000 
                 1.846660 
                 23.80 
               
               
                 2 
                 57.9139 
                 4.6578 
                 1.696800 
                 55.52 
               
               
                 3 
                 −430.8049 
                 0.1000 
                   
                   
               
               
                 4 
                 49.1887 
                 3.5211 
                 1.696800 
                 55.52 
               
               
                 5 
                 158.0589 
                 D5 (Variable) 
                   
                   
               
               
                 *6 
                 504.4641 
                 0.0800 
                 1.560930 
                 36.64 
               
               
                 7 
                 234.1101 
                 1.0000 
                 1.834810 
                 42.73 
               
               
                 8 
                 9.4881 
                 5.5305 
                   
                   
               
               
                 9 
                 −17.0787 
                 0.9276 
                 1.741000 
                 52.76 
               
               
                 10 
                 −1027.3916 
                 1.0145 
                   
                   
               
               
                 11 
                 34.5727 
                 2.6835 
                 1.808090 
                 22.74 
               
               
                 12 
                 −53.1261 
                 D12 (Variable) 
                   
                   
               
               
                 *13 
                 24.3966 
                 1.6530 
                 1.588870 
                 61.13 
               
               
                 14 
                 296.0192 
                 D14 (Variable) 
                   
                   
               
               
                 15 
                 ∞ 
                 1.5000 
                 (Stop) 
                   
               
               
                 16 
                 17.3960 
                 0.9000 
                 1.883000 
                 40.66 
               
               
                 17 
                 11.0000 
                 2.8505 
                 1.497820 
                 82.57 
               
               
                 18 
                 −48.0307 
                 1.5000 
                   
                   
               
               
                 19 
                 12.4669 
                 2.8380 
                 1.487490 
                 70.32 
               
               
                 20 
                 −14.1721 
                 0.9000 
                 1.851080 
                 40.12 
               
               
                 *21 
                 −35.5823 
                 0.1000 
                   
                   
               
               
                 22 
                 19.0885 
                 0.9000 
                 1.883000 
                 40.66 
               
               
                 23 
                 7.1245 
                 1.8774 
                 1.620040 
                 36.40 
               
               
                 24 
                 8.9496 
                 D24 (Variable) 
                   
                   
               
               
                 25 
                 −30.0000 
                 3.6500 
                 1.696800 
                 55.52 
               
               
                 26 
                 −19.7882 
                 BF 
                   
                   
               
               
                 Image 
                 ∞ 
                   
                   
                   
               
               
                 surface 
               
               
                   
               
            
           
           
               
            
               
                 [Aspherical surface data] 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 The 6th surface 
               
               
                   
                 κ = −1.9998 
               
               
                   
                 A4 = 2.80199E−05 
               
               
                   
                 A6 = −2.77907E−07 
               
               
                   
                 A8 = 2.24720E−09 
               
               
                   
                 A10 = −8.56636E−12 
               
               
                   
                 A12 = 0.00000E+00 
               
               
                   
                 The 13th surface 
               
               
                   
                 κ = 1.7623 
               
               
                   
                 A4 = −2.39838E−05 
               
               
                   
                 A6 = −7.89804E−08 
               
               
                   
                 A8 = 2.79454E−09 
               
               
                   
                 A10 = 0.00000E+00 
               
               
                   
                 A12 = 0.00000E+00 
               
               
                   
                 The 21th surface 
               
               
                   
                 κ = −0.1893 
               
               
                   
                 A4 = −9.56775E−06 
               
               
                   
                 A6 = −6.24519E−07 
               
               
                   
                 A8 = 1.01416E−08 
               
               
                   
                 A10 = 0.00000E+00 
               
               
                   
                 A12 = 0.00000E+00 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 W 
                 M 
                 T 
               
               
                   
               
            
           
           
               
            
               
                 [Various data] 
               
               
                 Zoom ratio 6.59 
               
            
           
           
               
               
               
               
               
            
               
                   
                 f 
                 10.29976 
                 39.99987 
                 67.89953 
               
               
                   
                 FNO 
                 3.64 
                 5.06 
                 5.81 
               
               
                   
                 ω 
                 39.73502 
                 10.92213 
                 6.56887 
               
               
                   
                 Y 
                 8.00 
                 8.00 
                 8.00 
               
               
                   
                 φ 
                 8.60 
                 9.90 
                 9.90 
               
               
                   
                 TL 
                 89.92002 
                 109.96784 
                 121.58326 
               
               
                   
                 BF 
                 13.25085 
                 13.25085 
                 13.25085 
               
            
           
           
               
            
               
                 [Variable distance data] 
               
            
           
           
               
               
               
               
               
            
               
                   
                 f 
                 10.29976 
                 39.99987 
                 67.89953 
               
               
                   
                 D5 
                 1.80000 
                 24.18110 
                 32.41506 
               
               
                   
                 D12 
                 25.02141 
                 7.23672 
                 2.58202 
               
               
                   
                 D14 
                 4.80996 
                 3.66893 
                 5.14775 
               
               
                   
                 D24 
                 5.25391 
                 21.84636 
                 28.40370 
               
            
           
           
               
            
               
                 [Amount of movement of focusing group upon focusing] 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Distance between 
                 1.00 m 
                 1.00 m 
                 1.00 m 
               
               
                   
                 object and image 
                   
                   
                   
               
               
                   
                 Amount of movement 
                 0.3072 
                 0.9550 
                 1.8445 
               
               
                   
               
            
           
           
               
            
               
                 [Lens group data] 
               
            
           
           
               
               
               
            
               
                 Group 
                 Group first 
                 Group focal 
               
               
                 number 
                 surface 
                 length 
               
               
                   
               
               
                 G1 
                 1 
                 68.26199 
               
               
                 G2 
                 6 
                 −12.46728 
               
               
                 G3 
                 13 
                 45.04911 
               
               
                 G4 
                 15 
                 40.55521 
               
               
                 G5 
                 25 
                 72.75019 
               
               
                   
               
            
           
           
               
            
               
                 [Values corresponding to conditional expressions] 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 Conditional expression(1)f3/ft = 0.633 
               
               
                   
                 Conditional expression(2)(−f2)/fw = 1.210 
               
               
                   
                 Conditional expression(3)f3/f4 = 1.111 
               
               
                   
                 Conditional expression(4)ν3 = 61.13 
               
               
                   
                 Conditional expression(5)(d3t − d3w)/fw = 0.033 
               
               
                   
                 Conditional expression(6)f4/ft = 0.597 
               
               
                   
                 Conditional expression(7)fR/fw = 7.063 
               
               
                   
                 Conditional expression(8)f3/ft = 0.663 
               
               
                   
                 Conditional expression(9)(d3t − d3w)/fw = 0.033 
               
               
                   
                 Conditional expression(10)fR/fw = 7.063 
               
               
                   
                 Conditional expression(11)(−f2)/fw = 1.210 
               
               
                   
                 Conditional expression(12)f4/ft = 0.597 
               
               
                   
                 Conditional expression(13)(d1t − d1w)/ft = 0.451 
               
               
                   
                 Conditional expression(14)(d2w − d2t)/ft = 0.330 
               
               
                   
                 Conditional expression(15)f3/ft = 0.663 
               
               
                   
                 Conditional expression(16)f4/ft = 0.597 
               
               
                   
                 Conditional expression(17)fR/fw = 7.063 
               
               
                   
                 Conditional expression(18)(−f2)/fw = 1.210 
               
               
                   
                 Conditional expression(19)(d3t − d3w)/fw = 0.033 
               
               
                   
                 Conditional expression(20)f3/ft = 0.663 
               
               
                   
                 Conditional expression(21)f4/fw = 3.937 
               
               
                   
                 Conditional expression(22)f3/f4 = 1.111 
               
               
                   
                 Conditional expression(23)(−f2)/ft = 0.184 
               
               
                   
                 Conditional expression(24)f1/ft = 1.005 
               
               
                   
                 Conditional expression(25)fR/fw = 7.063 
               
               
                   
               
            
           
         
       
     
     Table 2 shows that in the zoom optical system ZL 2  according to the present embodiment the conditional expressions (1) to (25) are satisfied. 
       FIGS. 6A, 6B and 6C  illustrate graphs showing various aberrations upon focusing on infinity regarding the zoom optical system ZL 2  according to Example 2 (spherical aberration, astigmatism, distortion, coma aberration, and lateral chromatic aberration), and  FIG. 6A  depicts a wide-angle end state,  FIG. 6B  depicts an intermediate focal length state, and,  FIG. 6C  depicts a telephoto end state.  FIGS. 7A, 7B and 7C  illustrate graphs showing various aberrations (spherical aberration, astigmatism, distortion, coma aberration, and lateral chromatic aberration) upon focusing on a short distance object regarding the zoom optical system ZL 2  according to Example 2 (1.00 m of distance between the object and image) where  FIG. 7A  depicts a wide-angle end state,  FIG. 7B  depicts an intermediate focal length state, and  FIG. 7C  depicts a telephoto end state.  FIGS. 8A, 8B, and 8C  illustrate graphs showing meridional lateral aberration when correcting image blur upon focusing on infinity regarding the zoom optical system ZL 2  according to Example 2 (shift amount of a vibration-free lens group=0.1 mm), where  FIG. 8A  depicts a wide-angle end state,  FIG. 8B  depicts an intermediate focal length state, and  FIG. 8C  depicts a telephoto end state. In the present example optical performance when controlling vibration, as illustrated in  FIGS. 8A, 8B and 8C , is illustrated in a meridional lateral aberration diagram corresponding to a screen center and ±5.6 mm of an image height. 
     As obvious based on each graph showing aberrations illustrated in  FIGS. 6A, 6B and 6C ,  FIGS. 7A, 7B and 7C , and  FIGS. 8A, 8B and 8C , in the zoom optical system ZL 2  according to Example 2, various aberrations are appropriately corrected covering a range from a wide-angle end state to a telephoto end state, and a range from an infinity focusing state to a short-distance focusing state, therefore high optical performance can be obtained. It is found that high image-forming performance can be obtained when correcting image blur. 
     EXAMPLE 3 
     Example 3 is described using  FIG. 9 ,  FIGS. 10A, 10B and 10C ,  FIGS. 11A, 11B and 11C ,  FIGS. 12A, 12B and 12C  and Table 3. The zoom optical system ZL (ZL 3 ) according to Example 3 comprises, as illustrated in  FIG. 9 , in order from an object along an optical axis, a first lens group G 1  having positive refractive power, a second lens group G 2  having negative refractive power, a third lens group G 3  having positive refractive power, a fourth lens group G 4  having positive refractive power, a fifth lens group G 5  having negative refractive power, and a sixth lens group G 6  having positive refractive power. An aperture stop S is provided between the third lens group G 3  and the fourth lens group G 4 , and the aperture stop S configures the fourth lens group G 4 . The sixth lens group G 6  is the lens group arranged closest to the image. 
     The first lens group G 1  is composed of, in order from the optical axis a cemented lens composed of a negative meniscus lens L 11  having a convex surface facing the object and a biconvex positive lens L 12 , and a positive meniscus lens L 13  having a convex surface facing the object. 
     The second lens group G 2  is composed of, in order from the object along optical axis, a negative meniscus lens L 21  having a convex surface facing the object, a biconcave negative lens L 22 , and a positive meniscus lens L 23  having a convex surface facing the object. Note that the negative lens L 22  is a glass-molded aspherical lens in which a lens surface on the object side is aspherical-shaped. 
     The third lens group G 3  is composed of a biconvex positive lens L 31 . Note that the positive lens L 31  is a glass-molded aspherical lens in which the lens surface on the object side is aspherical-shaped. 
     The fourth lens group G 4  is composed of, in order from the object along the optical axis, a fourth A sublens group G 4 A configured of a cemented lens composed of a negative meniscus lens L 41  having a convex surface facing the object and a biconvex positive lens L 42 , and a fourth B sublens group G 4 B configured of a cemented lens composed of a biconvex positive lens L 43  and a negative meniscus lens L 44  having a concave surface facing the object. Note that the negative meniscus lens L 44  is a glass-molded aspherical lens in which the lens surface arranged on the image side is aspherical-shaped. 
     The fifth lens group G 5  is composed of a negative meniscus lens L 51  having a convex surface facing the object. 
     The sixth lens group G 6  is composed of a positive meniscus lens L 61  having a concave surface facing the object. 
     In the zoom optical system ZL 3  according to the present example, the first lens group G 1  to the fifth lens group G 5  move along the optical axis upon zooming so that an air distance between the first lens group G 1  and the second lens group G 2 , an air distance between the second lens group G 2  and the third lens group G 3 , an air distance between the third lens group G 3  and the fourth lens group G 4 , an air distance between the fourth lens group G 4  and the fifth lens group G 5 , and an air distance between the fifth lens group G 5  and the sixth lens group G 6  respectively change. The sixth lens group G 6  is fixed to the image surface I. 
     Specifically speaking, the first lens group G 1 , the third lens group G 3 , the fourth lens group G 4 , and the fifth lens group G 5  move to the object side upon zooming from a wide-angle end state to a telephoto end state. The second lens group G 2  moves to the image side from a wide-angle end state to an intermediate focal length state, and moves to the object side from the intermediate focal length state to a telephoto end state. The aperture stop S moves to the object side together with the fourth lens group G 4 . 
     With this arrangement, upon zooming, the air distance between the first lens group G 1  and the second lens group G 2  increases, the air distance between the second lens group G 2  and the third lens group decreases, and the air distance between the third lens group and the fourth lens group G 4  decreases from a wide-angle end state to an intermediate focal length state, and increases from the intermediate focal length state to a telephoto end state, the air distance between the fourth lens group G 4  and the fifth lens group G 5  increases, and the air distance between the fifth lens group G 5  and the sixth lens group G 6  increases. The air distance between the aperture stop S and the third lens group G 3  decreases from a wide-angle end state to an intermediate focal length state, and increases from the intermediate focal length state to a telephoto end state. 
     Focusing is performed by moving the third lens group G 3  along the optical axis. Specifically speaking, this is performed by moving the third lens group G 3  to the image side along the optical axis upon focusing from an infinity object to a short-distance object. 
     When image blur is generated, a correction of image blur (vibration-controlled) on the image surface I is performed by moving the fourth A sub lens group G 4 A as a vibration-free lens group in a manner of having a component in the direction perpendicular to the optical axis. 
     Table 3 shows values of each data in Example 3. Surface numbers 1 to 24 in Table 3 correspond to each optical surface of m1 to m24 illustrated in  FIG. 9 . 
     
       
         
           
               
             
               
                 TABLE 3 
               
               
                   
               
             
            
               
                 [Lens Data] 
               
            
           
           
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
               
               
                 number 
                 R 
                 D 
                 nd 
                 νd 
               
               
                   
               
               
                 Object 
                 ∞ 
                   
                   
                   
               
               
                 surface 
                   
                   
                   
                   
               
               
                 1 
                 270.7698 
                 1.6000 
                 1.84666 
                 23.80 
               
               
                 2 
                 63.2289 
                 4.7857 
                 1.58913 
                 61.22 
               
               
                 3 
                 −180.7756 
                 0.1000 
                   
                   
               
               
                 4 
                 38.2772 
                 3.3872 
                 1.69680 
                 55.52 
               
               
                 5 
                 162.5542 
                 D5 (Variable) 
                   
                   
               
               
                 6 
                 222.4687 
                 0.9000 
                 1.72916 
                 54.61 
               
               
                 7 
                 8.6817 
                 5.3065 
                   
                   
               
               
                 *8 
                 −19.5238 
                 0.9000 
                 1.69680 
                 55.52 
               
               
                 9 
                 33.5766 
                 0.1038 
                   
                   
               
               
                 10 
                 19.7682 
                 2.5354 
                 1.84666 
                 23.80 
               
               
                 11 
                 434.3570 
                 D11 (Variable) 
                   
                   
               
               
                 *12 
                 26.1871 
                 1.7281 
                 1.58887 
                 61.13 
               
               
                 13 
                 −76.6701 
                 D13 (Variable) 
                   
                   
               
               
                 14 
                 ∞ 
                 1.7051 
                 (Stop) 
                   
               
               
                 15 
                 16.6153 
                 0.9002 
                 1.83400 
                 37.18 
               
               
                 16 
                 9.9827 
                 2.6157 
                 1.49782 
                 82.57 
               
               
                 17 
                 −36.7432 
                 1.5000 
                   
                   
               
               
                 18 
                 16.2913 
                 2.2592 
                 1.51823 
                 58.82 
               
               
                 19 
                 −17.2434 
                 0.9000 
                 1.85108 
                 40.12 
               
               
                 *20 
                 −31.3248 
                 D20 (Variable) 
                   
                   
               
               
                 21 
                 28.0868 
                 0.9000 
                 1.90265 
                 35.72 
               
               
                 22 
                 9.2493 
                 D22 (Variable) 
                   
                   
               
               
                 23 
                 −37.3758 
                 2.2000 
                 1.61772 
                 49.81 
               
               
                 24 
                 −18.1325 
                 BF 
                   
                   
               
               
                 Image 
                 ∞ 
                   
                   
                   
               
               
                 surface 
               
               
                   
               
            
           
           
               
            
               
                 [Aspherical surface data] 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 The 8th surface 
               
               
                   
                 κ = 1.0000 
               
               
                   
                 A4 = 2.09316E−05 
               
               
                   
                 A6 = −8.10797E−07 
               
               
                   
                 A8 = 2.75349E−08 
               
               
                   
                 A10 = −4.70299E−10 
               
               
                   
                 A12 = 2.62880E−12 
               
               
                   
                 The 12th surface 
               
               
                   
                 κ = 1.0000 
               
               
                   
                 A4 = −4.37334E−05 
               
               
                   
                 A6 = 3.04727E−07 
               
               
                   
                 A8 = −6.38106E−09 
               
               
                   
                 A10 = 0.00000E+00 
               
               
                   
                 A12 = 0.00000E+00 
               
               
                   
                 The 20th surface 
               
               
                   
                 κ = 1.0000 
               
               
                   
                 A4 = 2.28740E−05 
               
               
                   
                 A6 = −3.19205E−07 
               
               
                   
                 A8 = −1.46715E−10 
               
               
                   
                 A10 = 0.00000E+00 
               
               
                   
                 A12 = 0.00000E+00 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 W 
                 M 
                 T 
               
               
                   
               
            
           
           
               
            
               
                 [Various data] 
               
               
                 Zoom ratio 4.71 
               
            
           
           
               
               
               
               
               
            
               
                   
                 f 
                 10.30000 
                 32.00000 
                 48.51858 
               
               
                   
                 FNO 
                 3.53 
                 5.00 
                 5.72 
               
               
                   
                 ω 
                 39.75617 
                 13.57625 
                 9.11928 
               
               
                   
                 Y 
                 8.00 
                 8.00 
                 8.00 
               
               
                   
                 φ 
                 8.20 
                 8.80 
                 8.80 
               
               
                   
                 TL 
                 80.36557 
                 92.30690 
                 103.19342 
               
               
                   
                 BF 
                 13.30097 
                 13.30097 
                 13.30097 
               
            
           
           
               
            
               
                 [Variable distance data] 
               
            
           
           
               
               
               
               
               
            
               
                   
                 f 
                 10.30000 
                 32.00000 
                 48.51858 
               
               
                   
                 D5 
                 1.80638 
                 15.63570 
                 22.37678 
               
               
                   
                 D11 
                 18.74841 
                 4.51318 
                 2.11693 
               
               
                   
                 D13 
                 5.83635 
                 4.73970 
                 5.51292 
               
               
                   
                 D20 
                 1.50000 
                 3.72584 
                 3.97118 
               
               
                   
                 D22 
                 4.84649 
                 16.06454 
                 21.58766 
               
            
           
           
               
            
               
                 [Amount of movement of focusing group upon focusing] 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Distance between 
                 1.00 m 
                 1.00 m 
                 1.00 m 
               
               
                   
                 object and image 
                   
                   
                   
               
               
                   
                 Amount of movement 
                 0.1896 
                 0.4064 
                 0.6618 
               
               
                   
               
            
           
           
               
            
               
                 [Lens group data] 
               
            
           
           
               
               
               
            
               
                 Group 
                 Group first 
                 Group focal 
               
               
                 number 
                 surface 
                 length 
               
               
                   
               
               
                 G1 
                 1 
                 60.91787 
               
               
                 G2 
                 6 
                 −9.90833 
               
               
                 G3 
                 12 
                 33.35587 
               
               
                 G4 
                 14 
                 15.48045 
               
               
                 G5 
                 21 
                 −15.63253 
               
               
                 G6 
                 23 
                 54.62879 
               
               
                   
               
            
           
           
               
            
               
                 [Values corresponding to conditional expressions] 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 Conditional expression(1)f3/ft = 0.687 
               
               
                   
                 Conditional expression(2)(−f2)/fw = 0.962 
               
               
                   
                 Conditional expression(3)f3/f4 = 2.155 
               
               
                   
                 Conditional expression(4)ν3 = 61.13 
               
               
                   
                 Conditional expression(5)(d3t − d3w)/fw = 0.031 
               
               
                   
                 Conditional expression(6)f4/ft = 0.597 
               
               
                   
                 Conditional expression(7)fR/fw = 5.304 
               
               
                   
                 Conditional expression(8)f3/ft = 0.687 
               
               
                   
                 Conditional expression(9)(d3t − d3w)/fw = −0.031 
               
               
                   
                 Conditional expression(10)fR/fw = 5.304 
               
               
                   
                 Conditional expression(11)(−f2)/fw = 0.962 
               
               
                   
                 Conditional expression(13)(d1t − d1w)/ft = 0.424 
               
               
                   
                 Conditional expression(14)(d2w − d2t)/ft = 0.343 
               
               
                   
                 Conditional expression(15)f3/ft = 0.687 
               
               
                   
                 Conditional expression(17)fR/fw = 5.304 
               
               
                   
                 Conditional expression(18)(−f2)/fw = 0.962 
               
               
                   
                 Conditional expression(19)(d3t − d3w)/fw = −0.031 
               
               
                   
                 Conditional expression(20)f3/ft = 0.687 
               
               
                   
                 Conditional expression(21)f4/fw = 1.503 
               
               
                   
                 Conditional expression(22)f3/f4 = 2.155 
               
               
                   
                 Conditional expression(23) (−f2)/ft = 0.204 
               
               
                   
                 Conditional expression(24)f1/ft = 1.256 
               
               
                   
                 Conditional expression(25)fR/fw = 5.304 
               
               
                   
               
            
           
         
       
     
     Base on Table 3, it is found that in the zoom optical system ZL 3  according to the present embodiment, the conditional expressions (1) to (11), (13) to (15), and (17) to (25) are satisfied. 
     FIGS. 10 A,  10 B and  10 C illustrate graphs showing various aberrations (spherical aberration, astigmatism, distortion, coma aberration, and lateral chromatic aberration) upon focusing on infinity regarding the zoom optical system ZL 3  according to Example  3 , where  FIG. 10A  depicts a wide-angle end state,  FIG. 10B  depicts an intermediate focal length state, and  FIG. 10C  depicts a telephoto end state. FIGS. 11 A,  11 B and  11 C illustrate graphs showing various aberrations (spherical aberration, astigmatism, distortion, coma aberration, and lateral chromatic aberration) upon focusing on a short-distance object regarding the zoom optical system ZL 3  according to Example 3 (1.00 m of distance between the object and image), where  FIG. 11A  depicts a wide-angle end state,  FIG. 11B  depicts an intermediate focal length state, and  FIG. 11C  depicts a telephoto end state.  FIGS. 12A, 12B, and 12C  illustrate graphs showing meridional lateral aberration when correcting image blur upon focusing on infinity regarding the zoom optical system ZL 3  according to Example 3 (shift amount of the vibration-free lens group=0.1 mm), where  FIG. 12A  depicts a wide-angle end state,  FIG. 12B  depicts an intermediate focal length state, and  FIG. 12C  depicts a telephoto end state. In the present example, optical performance when controlling vibration, as illustrated in  FIGS. 12A, 12  B and  12 C, is illustrated in a meridional lateral aberration diagram corresponding to a screen center and an image height ±5.6 mm. 
     As found based on each graph showing aberrations illustrated in  FIGS. 10A, 10B and 10C , FIGS. 11 A,  11 B and  11 C, and  FIGS. 12A, 12B and 12C , in the zoom optical system ZL 3  according to Example 3, various aberrations are appropriately corrected covering a range of from a wide-angle end state to a telephoto end state, and a range from an infinity focusing state to a short-distance object, therefore high optical performance can be obtained. It is found that high image-forming performance can be obtained upon correcting image blur. 
     EXAMPLE 4 
     Example 4 is described using  FIG. 13 ,  FIGS. 14A, 14B and 14C ,  FIGS. 15A, 15B and 15C ,  FIGS. 16A, 16B and 16C  and Table 4. The zoom optical system ZL (ZL 4 ) according to Example 4 comprises, as illustrated in  FIG. 13 , in order from an object along an optical axis, a first lens group G 1  having positive refractive power, a second lens group G 2  having negative refractive power, a third lens group G 3  having positive refractive power, and a fourth lens group G 4  having positive refractive power. An aperture stop S is provided between the third lens group and the fourth lens group G 4 , and the aperture stop S configures the fourth lens group G 4 . The fourth lens group G 4  is the lens group arranged closest to the image. 
     The first lens group G 1  is composed of, in order from the object along the optical axis, a cemented lens composed of a negative meniscus lens L 11  having a convex surface facing the object and a positive meniscus lens L 12  having a convex surface facing the object, and a positive meniscus lens L 13  having a convex surface to the object side. 
     The second lens group G 2  is composed of, in order from the object along the optical axis, a biconcave negative lens L 21 , a biconcave lens negative lens L 22 , and a cemented lens composed of a biconvex positive lens L 23  and a biconcave negative lens L 24 . Note that the negative lens L 22  is a glass-molded aspherical lens in which the lens surface on the object side is aspherical-shaped. 
     The third lens group G 3  is composed of a positive meniscus lens L 31  having a convex surface facing the object. Note that the positive meniscus lens L 31  is a glass-molded aspherical lens in which the lens surface on the object side is aspherical-shaped. 
     The fourth lens group G 4  is composed of, in order from the object side along the optical axis, a fourth A sublens group G 4 A configured of a cemented lens composed of a negative meniscus lens L 41  having a convex surface facing the object and a biconvex positive lens L 42 , a cemented lens composed of a biconvex positive lens L 43  and a biconcave negative lens L 44 , and a fourth B sublens group G 4 B configured of a biconvex positive lens L 45 . Note that the negative lens L 44  is a glass-molded aspherical lens in which the lens surface on the image side is aspherical-shaped. 
     In zoom optical system ZL 4  according to the present example, the first lens group G 1  to the fourth lens group G 4  move along the optical axis upon zooming so that an air distance between the first lens group G 1  and the second lens group G 2 , an air distance between the second lens group G 2  and the third lens group G 3 , and an air distance between the third lens group G 3  and the fourth lens group G 4  respectively change. 
     Specifically speaking, the first lens group G 1  to the fourth lens group G 4  move to the object side upon zooming from a wide-angle end state to a telephoto end state. The aperture stop S moves to the object side together with the fourth lens group G 4 . 
     With this arrangement, upon zooming, the air distance between the first lens group G 1  and the second lens group G 2  increases, the air distance between the second lens group G 2  and the third lens group decreases, and the air distance between the third lens group and the fourth lens group G 4  decreases from a wide-angle end state to an intermediate focal length state, and increases from the intermediate focal length state to a telephoto end state. An air distance between the aperture stop S and the third lens group G 3  decreases from a wide-angle end state to an intermediate focal length state, and increases from the intermediate focal length state to a telephoto end state. 
     Focusing is performed by moving the third lens group G 3  to the optical axis along the optical axis. Specifically speaking, this is performed by moving the third lens group G 3  to the image side along the optical axis upon focusing from an infinity object to a short-distance object. 
     When image blur is generated, a correction of image blur (vibration-controlled) on the image surface I is performed by moving the fourth A sublens group G 4 A as a vibration-free lens group in a manner of having a component in a direction perpendicular to the optical axis. 
     Table 4 below shows values of each data in Example 4. Surface numbers 1 to 23 in Table 4 correspond to each optical surface of m1 to m23 illustrated in  FIG. 13 . 
     
       
         
           
               
             
               
                 TABLE 4 
               
               
                   
               
             
            
               
                 [Lens Data] 
               
            
           
           
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
               
               
                 number 
                 R 
                 D 
                 nd 
                 νd 
               
               
                   
               
               
                 Object 
                 ∞ 
                   
                   
                   
               
               
                 surface 
                   
                   
                   
                   
               
               
                 1 
                 77.5097 
                 1.0000 
                 1.75520 
                 27.57 
               
               
                 2 
                 36.9718 
                 5.6271 
                 1.58913 
                 61.22 
               
               
                 3 
                 167.7984 
                 0.1000 
                   
                   
               
               
                 4 
                 42.4933 
                 4.6381 
                 1.69680 
                 55.52 
               
               
                 5 
                 206.8356 
                 D5 (Variable) 
                   
                   
               
               
                 6 
                 −873.2108 
                 1.0000 
                 1.77250 
                 49.62 
               
               
                 7 
                 7.8543 
                 3.6373 
                   
                   
               
               
                 *8 
                 −26.1695 
                 1.0000 
                 1.69680 
                 55.52 
               
               
                 9 
                 27.7405 
                 0.5875 
                   
                   
               
               
                 10 
                 15.7767 
                 2.7220 
                 1.75520 
                 27.57 
               
               
                 11 
                 −33.7553 
                 0.6000 
                 1.79500 
                 45.31 
               
               
                 12 
                 131.6242 
                 D12 (Variable) 
                   
                   
               
               
                 *13 
                 16.5456 
                 1.4427 
                 1.58887 
                 61.13 
               
               
                 14 
                 214.1576 
                 D14 (Variable) 
                   
                   
               
               
                 15 
                 ∞ 
                 1.8000 
                 (Stop) 
                   
               
               
                 16 
                 10.9743 
                 1.0000 
                 1.80440 
                 39.61 
               
               
                 17 
                 6.8392 
                 2.4312 
                 1.49782 
                 82.57 
               
               
                 18 
                 −31.7167 
                 1.8000 
                   
                   
               
               
                 19 
                 12.8502 
                 1.7243 
                 1.51680 
                 63.88 
               
               
                 20 
                 −34.8585 
                 2.1512 
                 1.85108 
                 40.12 
               
               
                 *21 
                 10.5402 
                 5.0997 
                   
                   
               
               
                 22 
                 17.8216 
                 2.0000 
                 1.54814 
                 45.51 
               
               
                 23 
                 −380.5160 
                 BF 
                   
                   
               
               
                 Image 
                 ∞ 
                   
                   
                   
               
               
                 surface 
               
               
                   
               
            
           
           
               
            
               
                 [Aspherical surface data] 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 The 8th surface 
               
               
                   
                 κ = 1.0000 
               
               
                   
                 A4 = 9.05226E−06 
               
               
                   
                 A6 = −3.64342E−07 
               
               
                   
                 A8 = 1.64340E−08 
               
               
                   
                 A10 = −2.40084E−10 
               
               
                   
                 A12 = 2.62880E−12 
               
               
                   
                 The 13th surface 
               
               
                   
                 κ = 1.0000 
               
               
                   
                 A4 = −3.32881E−05 
               
               
                   
                 A6 = −5.73267E−07 
               
               
                   
                 A8 = 1.34421E−08 
               
               
                   
                 A10 = 0.00000E+00 
               
               
                   
                 A12 = 0.00000E+00 
               
               
                   
                 The 21th surface 
               
               
                   
                 κ = 1.0000 
               
               
                   
                 A4 = 4.36460E−05 
               
               
                   
                 A6 = −1.73977E−06 
               
               
                   
                 A8 = −8.65204E−08 
               
               
                   
                 A10 = 4.98963E−09 
               
               
                   
                 A12 = 0.00000E+00 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 W 
                 M 
                 T 
               
               
                   
               
            
           
           
               
            
               
                 [Various data] 
               
               
                 Zoom ratio 4.71 
               
            
           
           
               
               
               
               
               
            
               
                   
                 f 
                 10.30000 
                 35.00000 
                 48.50000 
               
               
                   
                 FNO 
                 3.65 
                 5.61 
                 5.72 
               
               
                   
                 ω 
                 43.22847 
                 12.93946 
                 9.34123 
               
               
                   
                 Y 
                 8.00 
                 8.00 
                 8.00 
               
               
                   
                 φ 
                 7.50 
                 7.50 
                 7.50 
               
               
                   
                 TL 
                 75.14938 
                 98.84478 
                 107.15583 
               
               
                   
                 BF 
                 13.51683 
                 29.96775 
                 30.85637 
               
            
           
           
               
            
               
                 [Variable distance data] 
               
            
           
           
               
               
               
               
               
            
               
                   
                 f 
                 10.30000 
                 35.00000 
                 48.50000 
               
               
                   
                 D5 
                 2.09904 
                 21.23006 
                 29.53997 
               
               
                   
                 D12 
                 14.54727 
                 2.99470 
                 1.80000 
               
               
                   
                 D14 
                 4.62522 
                 4.29125 
                 4.59848 
               
            
           
           
               
            
               
                 [Amount of movement of focusing group upon focusing] 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Distance between 
                 1.00 m 
                 1.00 m 
                 1.00 m 
               
               
                   
                 object and image 
                   
                   
                   
               
               
                   
                 Amount of movement 
                 0.1532 
                 0.4169 
                 0.7343 
               
               
                   
               
            
           
           
               
            
               
                 [Lens group data] 
               
            
           
           
               
               
               
            
               
                 Group 
                 Group first 
                 Group focal 
               
               
                 number 
                 surface 
                 length 
               
               
                   
               
               
                 G1 
                 1 
                 67.90812 
               
               
                 G2 
                 6 
                 −9.06196 
               
               
                 G3 
                 13 
                 30.36765 
               
               
                 G4 
                 15 
                 27.85994 
               
               
                   
               
            
           
           
               
            
               
                 [Values corresponding to conditional expressions] 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 Conditional expression(20)f3/ft = 0.626 
               
               
                   
                 Conditional expression(21)f4/fw = 2.705 
               
               
                   
                 Conditional expression(22)f3/f4 = 1.090 
               
               
                   
                 Conditional expression(23)(−f2)/ft = 0.187 
               
               
                   
                 Conditional expression(24)f1/ft = 1.400 
               
               
                   
               
            
           
         
       
     
     Based on Table 4, it is found that in the zoom optical system ZL 4  according to the present embodiment the conditional expressions (20) to (24) are satisfied. 
       FIGS. 14A, 14B and 14C  illustrate graphs showing various aberrations (spherical aberration, astigmatism, distortion, coma aberration, and lateral chromatic aberration) upon focusing on infinity regarding the zoom optical system ZL 4  according to Example 4, where  FIG. 14A  depicts a wide-angle end state,  FIG. 14B  depicts an intermediate focal length state, and  FIG. 14C  depicts a telephoto end state.  FIGS. 15A, 15B and 15C  illustrate graphs showing various aberrations (spherical aberration, astigmatism, distortion, coma aberration, and lateral chromatic aberration) upon focusing on a short-distance object regarding the zoom optical system ZL 4  according to Example 4 (1.00 m of distance between the object and image), where  FIG. 15A  depicts a wide-angle end state,  FIG. 15B  depicts an intermediate focal length state, and  FIG. 15C  shows a telephoto end state.  FIGS. 16A, 16B, and 16C  illustrate graphs showing meridional lateral aberration when correcting image blur upon focusing on infinity regarding the zoom optical system ZL 4  according to Example 4 (shift amount of a vibration-free lens group=0.1 mm), where  FIG. 16A  depicts a wide-angle end state,  FIG. 16B  depicts an intermediate focal length state, and  FIG. 16C  depicts a telephoto end state. In the present example optical performance when controlling vibration, as illustrated in  FIGS. 16A, 16B and 16C , is illustrated in a meridional lateral aberration diagram corresponding to a screen center and an image height ±5.6 mm. 
     As found based on each graph showing aberrations illustrated in  FIGS. 14A, 14B and 14C ,  FIGS. 15A, 15B and 15C , and  FIGS. 16A, 16B and 16C , in the zoom optical system ZL 4  according to Example 4, various aberrations are appropriately corrected covering a range of from a wide-angle end state to a telephoto end state, and a range from an infinity focusing state to a short-distance focusing state, therefore high optical performance can be obtained. It is found that high image-forming performance can be obtained upon correcting image blur. 
     According to each example above, it is possible to realize the zoom optical system in which the focusing lens group is small, and which has high optical performance upon zooming and focusing. 
     According to each example above, it is possible to realize the zoom optical system having high optical performance over a whole zoom range. 
     According to each example above, it is possible to realize the zoom optical system having high optical performance also when correcting image blur. 
     In order to make the present invention understandable, the descriptions were made with elements of the embodiments, however, needless to say, the present invention is not limited to the above. The following contents can be suitably adopted within a range which does not spoil the optical performance of the zoom optical system of the present application. 
     Although as examples of values of the zoom optical system ZL according to the first to fourth embodiments, four groups, five groups, and six group configurations are exampled, however they are not limited to those configurations, therefore another group configuration (for instance, seven groups, etc.) can be adopted. Specifically speaking, this is applicable to a configuration in which a lens or a lens group is added closest to the object, or a configuration in which a lens or a lens group is added closest to the image. Note that a lens group means part which has at least one lens separated with an air distance which changes upon zooming. 
     In the zoom optical systems ZL according to the first to fourth embodiments, in order to perform focusing from an infinity object to a short-distance object, it is appreciated that part of lens group, a whole one lens group, or a plurality of lens groups is configured to move in the optical axis direction as a focusing lens group. Although in the present embodiment the third lens group G 3  is exampled as a focusing lens group, however, at least part of the second lens group G 2 , at least part of the third lens group G 3 , at least part of the fourth lens group G 4 , or at least part of the fifth lens group G 5  can be configured as the focusing lens group. This focusing lens groups are applicable to autofocus, and suitable for driving by a electromotor for the autofocus (for instance, an ultrasonic motor, etc.). 
     In the zoom optical systems ZL according to the first to fourth embodiments, although the fourth A sublens group G 4 A is exampled as a configuration in which image blur generated due to camera shake, etc. is corrected by moving any one of a whole lens group or partial lens group as a vibration-free lens group in a manner of having a component in the direction perpendicular to the optical axis, or rotating and moving (swinging) them in an inner surface direction including the optical axis, this is not limited as above, for example, at least part of the third lens group G 3 , at least part of the fourth lens group G 4 , or at least part of the fifth lens group G 5  may be configured of the vibration-free lens group. 
     In the zoom optical systems ZL according to the first to fourth embodiments, a lens surface may be configured of a spherical surface or a plane, or configured of an aspherical surface. In case that a lens surface is a spherical surface or a plane, it is possible to easily have lens processing and an assembly adjustment, and to prevent degradation of optical performance due to errors of the processing and the assembly adjustment, thus it is preferable. It is preferable because there is less degradation of depiction performance when an image surface is shifted. In case that a lens surface is an aspherical surface, the aspherical surface may be formed as any one of an aspherical surface which is formed through grinding processing, a glass mold aspherical surface which glass is formed into an aspherical surface configuration using a mold, and a complexed aspherical surface which resin is formed on a surface of glass into an aspherical surface configuration. It is appreciated that a lens surface is formed as a diffractive surface, additionally a lens is formed as a graded-index lens (GRIN lens) or a plastic lens. 
     In the zoom optical systems ZL according to the first to fourth embodiments, it is preferable that the aperture stop S is disposed in the fourth lens group G 4 , or in its vicinity. Note that it is appreciated that instead of providing a member as an aperture stop, the role is substituted with a frame of the lens. 
     In the zoom optical systems ZL according to the first to fourth embodiments, an antireflection film having high transmittivity in a large wavelength band may be applied to each lens surface in order to reduce flare and ghost and attain high optical performance with high contrast. 
     EXPLANATION OF NUMERALS AND CHARACTERS 
     ZL (ZL 1 -ZL 4 ) Zoom optical system 
     G 1  First lens group 
     G 2  Second lens group 
     G 3  Third lens group 
     G 4  Fourth lens group 
     G 4 A Fourth A sublens group 
     G 4 B Fourth B sublens group 
     G 5  Fifth lens group 
     G 6  Sixth lens group 
     S Aperture stop 
     I Image surface 
       1  Camera (Optical device)