Variable magnification optical system, optical apparatus and method for manufacturing variable magnification optical system

Abstract

A variable power optical system used for an optical apparatus, such as a camera, includes, 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 or negative refractive power. The distances between lens groups change upon zooming from a wide-angle end state to a telephoto end state. The third lens group comprises, in order from the object, a first positive lens, a second positive lens, a first negative lens, a second negative lens and a third positive lens. The third lens group includes a vibration-isolating lens group which can move so as to have a movement component in a direction orthogonal to the optical axis upon correcting camera shake.

1 - 52 . (canceled) 
     
     
         53 . A variable power 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 or negative refractive power,   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 changing respectively upon zooming from a wide-angle end state to a telephoto end state,   the third lens group comprising, in order from the object, a first positive lens, a second positive lens, a first negative lens, a second negative lens and a third positive lens,   the third lens group comprising a vibration-isolating lens group which can move so as to have a movement component in a direction orthogonal to the optical axis upon correcting camera shake.   
     
     
         54 . The variable power optical system according to  claim 53 , wherein
 the vibration-isolating lens group consists of one cemented lens.   
     
     
         55 . The variable power optical system according to  claim 53 , wherein
 the vibration-isolating lens group consists of one negative lens and one positive lens.   
     
     
         56 . The variable power optical system according to  claim 53 , wherein
 the variable power optical system consists of the first lens group, the second lens group, the third lens group and the fourth lens group.   
     
     
         57 . The variable power optical system according to  claim 53 , including, in order from the object and next to the third positive lens, a fourth positive lens, a third negative lens and a fifth positive lens. 
     
     
         58 . The variable power optical system according to  claim 53 , wherein
 the following conditional expression is satisfied:
   0.4<(− f 2)/( fw×ft ) 1/2 <1.1
 
   where f2 denotes a focal length of the second lens group, fw denotes a focal length of the variable power optical system in the wide-angle end state, and ft denotes a focal length of the variable power optical system in the telephoto end state.   
     
     
         59 . The variable power optical system according to  claim 53 , wherein
 the following conditional expression is satisfied:
   ν dO >60
 
   where νdO denotes an Abbe number of a medium of the first positive lens.   
     
     
         60 . The variable power optical system according to  claim 53 , wherein
 the first lens group moves toward an image at first and then moves toward the object upon zooming from the wide-angle end state to the telephoto end state.   
     
     
         61 . The variable power optical system according to  claim 53 , wherein
 the third lens group includes, in order from the object: a first sub-group of which position with respect to an image plane is fixed upon correcting camera shake; and a second sub-group serving as a vibration-isolating lens group which has positive refractive power, and   the following conditional expression is satisfied:
   1.5< fv×FNOw/fX< 5.0 
   where fX denotes a combined focal length of the first sub-group and the second sub-group, fv denotes a focal length of the second sub-group, and FNOw denotes an F number of the variable power optical system in the wide-angle end state.   
     
     
         62 . The variable power optical system according to  claim 53 , wherein
 the following conditional expression is satisfied:
   1.0< f 3/Δ T 3<2.2
 
   where ΔT3 denotes a moving distance of the third lens group upon zooming from the wide-angle end state to the telephoto end state, and f3 denotes a focal length of the third lens group.   
     
     
         63 . The variable power optical system according to  claim 53 , wherein
 the following conditional expression is satisfied:
   4.0< fr/fw< 11.0 
   where fr denotes a focal length of a final lens group closest to an image, and fw denotes a focal length of the variable power optical system in the wide-angle end state.   
     
     
         64 . The variable power optical system according to  claim 53 , wherein
 the following conditional expression is satisfied:
   0.9< f 3/( fw×ft ) 1/2 <2.0 
   where f3 denotes a focal length of the third lens group, fw denotes a focal length of the variable power optical system in the wide-angle end state, and ft denotes a focal length of the variable power optical system in the telephoto end state.   
     
     
         65 . The variable power optical system according to  claim 53 , wherein
 the third lens group includes, in order from the object: a first sub-group of which position with respect to an image plane is fixed upon correcting camera shake; and a second sub-group serving as the vibration-isolating lens group which has positive refractive power,   the second sub-group comprises at least one positive lens, and   the following conditional expression is satisfied:
   ( ndVR+ 0.0052×ν dVR− 1.965)<0
 
   ν dVR> 60
 
   where ndVR denotes a refractive index of a medium of the positive lens included in the second sub-group at d-line, and νdVR denotes an Abbe number of the medium of the positive lens included in the second sub-group.   
     
     
         66 . The variable power optical system according to  claim 53 , wherein
 an aperture stop is provided between the second lens group and the third lens group.   
     
     
         67 . An optical apparatus comprising the variable power optical system according to  claim 53 . 
     
     
         68 . A method of manufacturing a variable power optical system, comprising:
 arranging, in a lens barrel and 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 or negative refractive power,   the first to fourth lens groups being arranged such 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 respectively upon zooming from a wide-angle end state to a telephoto end state,   with the third lens group comprising, in order from the object, a first positive lens, a second positive lens, a first negative lens, a second negative lens and a third positive lens, and   the third lens group comprising a vibration-isolating lens group which can move so as to have a movement component in a direction orthogonal to the optical axis upon correcting camera shake.