Variable power optical system, optical device and method for manufacturing variable power optical system

Abstract

A variable magnification optical system is provided which includes, in order from an object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4, and a subsequent lens group GR. Upon zooming, each of distances between the first lens group G1 and the second lens group G2, between the second lens group G2 and the third lens group G3, between the third lens group G3 and the fourth lens group G4, between the fourth lens group G4 and the subsequent lens group GR is varied, and upon focusing, the third lens group G3 is moved along an optical axis. A predetermined condition is satisfied. Consequently, the optical system enables a focusing lens group to be downsized and made light and also enables high speed auto focusing and quietness upon auto focusing to be realized without increasing the size of a barrel. Variation in aberration upon zooming from a wide-angle end state to a telephoto end state and variation in aberration upon focusing from an infinite distance object to a close distance object are well suppressed. Also, an optical apparatus and a method for manufacturing the variable magnification optical system are provided.

1 - 33 . (canceled) 
     
     
         34 . A variable magnification optical system comprising, in consecutive order from an object side:
 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;   a fifth lens group having negative refractive power; and   a sixth lens group having positive refractive power;   upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group being varied, a distance between the second lens group and the third lens group being varied, a distance between the third lens group and the fourth lens group being varied, a distance between the fourth lens group and the fifth lens group being varied, and a distance between the fifth lens group and the sixth lens group being varied;   the following conditional expression being satisfied:
   0.60< f 3/ f 4<1.30 
   where f3 denotes a focal length of the third lens group; and f4 denotes a focal length of the fourth lens group.   
     
     
         35 . The variable magnification optical system according to  claim 34 , wherein upon zooming from the wide-angle end state to the telephoto end state, the first lens group is moved toward the object side. 
     
     
         36 . The variable magnification optical system according to  claim 34 , wherein upon zooming from the wide-angle end state to the telephoto end state, the third lens group is moved toward the object side. 
     
     
         37 . The variable magnification optical system according to  claim 34 , wherein upon zooming from the wide-angle end state to the telephoto end state, the fourth lens group is moved toward the object side. 
     
     
         38 . The variable magnification optical system according to  claim 34 , wherein upon zooming from the wide-angle end state to the telephoto end state, the fifth lens group is moved toward the object side. 
     
     
         39 . The variable magnification optical system according to  claim 34 , wherein the first lens group consists of three lenses. 
     
     
         40 . The variable magnification optical system according to  claim 34 , wherein a focusing lens group is provided on a nearer side to an image plane than the first lens group. 
     
     
         41 . The variable magnification optical system according to  claim 40 , wherein the focusing lens group is moved toward the image plane side for focusing from an infinite distance object to a close distance object. 
     
     
         42 . The variable magnification optical system according to  claim 34 , wherein a vibration reduction lens group is provided on a nearer side to an image plane than the first lens group. 
     
     
         43 . The variable magnification optical system according to  claim 34 , wherein
 the following conditional expression is satisfied:
   0.11<(− f 2)/ f 1<0.19
 
   where f2 denotes a focal length of the second lens group; and f1 denotes a focal length of the first lens group.   
     
     
         44 . A variable magnification optical system comprising, in consecutive order from an object side:
 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; and   a subsequent lens group comprising at least one lens group;   upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group being varied, a distance between the second lens group and the third lens group being varied, a distance between the third lens group and the fourth lens group being varied, a distance between the fourth lens group and the subsequent lens group being varied, and when the subsequent lens group comprises a plurality of lens groups, each distance between adjacent lens groups of the plurality of lens groups is varied;   a focusing lens group provided on a nearer side to the image side than the first lens group, the focusing lens group being moved toward the image side for focusing from an infinite distance object to a close distance object; and   a vibration reduction lens group provided on a nearer side to an image plane than the first lens group.   
     
     
         45 . The variable magnification optical system according to  claim 44 , wherein the following conditional expression is satisfied.
   0.60< f 3/ f 4<1.30   where f3 denotes a focal length of the third lens group; and f4 denotes a focal length of the fourth lens group.   
     
     
         46 . The variable magnification optical system according to  claim 44 , wherein upon zooming from the wide-angle end state to the telephoto end state, the first lens group is moved toward the object side. 
     
     
         47 . The variable magnification optical system according to  claim 44 , wherein upon zooming from the wide-angle end state to the telephoto end state, the third lens group is moved toward the object side. 
     
     
         48 . The variable magnification optical system according to  claim 44 , wherein the subsequent lens group includes a fifth lens group; and
 upon zooming from the wide-angle end state to the telephoto end state, the fifth lens group is moved toward the object side.   
     
     
         49 . The variable magnification optical system according to  claim 44 , wherein the first lens group consists of three lenses. 
     
     
         50 . The variable magnification optical system according to  claim 44 , wherein the following conditional expression is satisfied:
   0.11<(− f 2)/ f 1<0.19
   where f2 denotes a focal length of the second lens group, and f1 denotes a focal length of the first lens group.   
     
     
         51 . The variable magnification optical system according to  claim 44 , wherein the following conditional expression is satisfied:
   2.00<(− f 4)/ f 5<4.00
   where f4 denotes a focal length of the fourth lens group, and f5 denotes a focal length of the fifth lens group.   
     
     
         52 . A method for manufacturing a variable magnification optical system A comprising, in consecutive order from an object side along an optical axis: 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; a fifth lens group having negative refractive power; and a sixth lens group having positive refractive power; or
 a variable magnification optical system B comprising, in consecutive order from an object side: 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; and a subsequent lens group comprising at least one lens group;   the method of the variable magnification optical system A comprising the steps of:   disposing the lens groups such that, upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group is varied, a distance between the second lens group and the third lens group is varied, a distance between the third lens group and the fourth lens group is varied, a distance between the fourth lens group and the fifth lens group is varied, and a distance between the fifth lens group and the sixth lens group is varied; and   configuring the third and fourth lens groups such that the following conditional expression is satisfied:
   0.60< f 3/ f 4<1.30 
   where f3 denotes a focal length of the third lens group, f4 denotes a focal length of the fourth lens group;   the method of the variable magnification optical system B comprising the steps of:   disposing the lens groups such that, upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group is varied, a distance between the second lens group and the third lens group is varied, a distance between the third lens group and the fourth lens group is varied, a distance between the fourth lens group and the subsequent lens group is varied, and when the subsequent lens group comprises a plurality of lens groups, each distance between adjacent lens groups of the plurality of lens groups is varied;   disposing a focusing lens group on the image side of the first lens group such that the focusing lens group is moved toward the image side for focusing from an infinite distance object to a close distance object;   disposing a vibration reduction lens group on the image side of the first lens group; and   configuring the third and fourth lens groups such that the following conditional expression is satisfied:
   0.60< f 3/ f 4<1.30 
   where f3 denotes a focal length of the third lens group, f4 denotes a focal length of the fourth lens group.