Patent ID: 7558004

Claim:
A variable power optical system comprising: in order from an object side of the variable power optical system, a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a positive refractive power; and a fourth lens group having a negative refractive power and comprising a plurality of sub lens groups, wherein the second lens group is moved along an optical axis thereof to vary a power of the variable power optical system, and the third lens group is moved along the optical axis thereof to correct image surface variation caused by the varying of the power and to perform focusing of the variable power optical system, and the fourth lens group is fixed at the time of the varying of the power and the focusing, and one of the plurality of sub lens groups is a cemented lens including a positive lens and a negative lens placed in order from the object side, and the cemented lens moves in a direction perpendicular to the optical axis to move an image.