Patent ID: 7907351

Claim:
A variable power optical system comprising: in order from an object side thereof, a first lens group having a negative refractive power and including a negative lens group and a positive lens group in order from the object side; a stop; and a second lens group having a positive refractive power and including a sub-lens group having a positive refractive power as a whole and arranged on the most object side thereof, the sub-lens group including, in order from the object side, a first lens having a positive refractive power having at least one aspherical surface, a second lens having a negative refractive power, and a third lens having a positive refractive power, wherein the second lens group includes five lenses including the sub-lens group, a negative meniscus lens having a concave surface on the image side, and a positive lens in order from the object side, the second lens group is moved to the object side along an optical axis thereof to perform a variable power operation from a wide angle end to a telephoto end of the variable power optical system, and the first lens group is moved to make a correction of an image plane position in accordance with the variable power operation, wherein the first lens of the sub-lens group is a biconvex lens, the second lens of the sub-lens group is a biconcave lens, and the third lens of the sub-lens group is a biconvex lens, and wherein an air distance along the optical axis exists between the first and second lens.