Variable magnification optical system, optical device, and method for producing variable magnification

Abstract

Comprising, in order from an object side: a first lens group G 1 having positive refractive power; a second lens group G 2 having negative refractive power; an aperture stop S; a third lens group G 3 having positive refractive power; and a fourth lens group G 4 having positive refractive power; upon zooming from a wide-angle end state to a telephoto end state, the distance between the first lens group G 1 and the second lens group G 2 , the distance between the second lens group G 2 and the aperture stop S, the distance between the aperture stop S and the third lens group G 3 , and the distance between the third lens group G 3 and the fourth lens group G 4 being varied, and the distance between the aperture stop S and the fourth lens group G 4 being constant; and a predetermined conditional expression being satisfied, thereby providing a variable magnification optical system which is compact in size and has a high variable magnification ratio and high optical performance, an optical apparatus, and a method for manufacturing a variable magnification optical system.

1 . A variable magnification optical system comprising, in order from an object side: a first lens group having positive refractive power; a second lens group having negative refractive power; an aperture stop; a third lens group having positive refractive power; and a fourth 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, a distance between the second lens group and the aperture stop, a distance between the aperture stop and the third lens group, and a distance between the third lens group and the fourth lens group being varied, and a distance between the aperture stop and the fourth lens group being constant; and   the following conditional expression being satisfied:
   5.300< f 1/ fw< 8.000 
   where fw denotes a focal length of the variable magnification optical system in the wide angle end state, and f1 denotes a focal length of the first lens group.   
     
     
         2 - 28 . (canceled)