Patent ID: 9726869
Date: 2017-08-08
CPC Classifications: G02B

Claim:
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; 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, the first lens group being fixed in a position in the direction of the optical axis, and at least the second lens group and the third lens group being moved in the direction of the optical axis such that a distance between the first lens group and the second lens group is increased and a distance between the second lens group and the third lens group is decreased; at least a portion of the first lens group to the fourth lens group being moved to have a component in a direction perpendicular to the optical axis; and the following conditional expression being satisfied: where f13 wherein magnification of the second lens group varies so as to stride across the equi-magnification and the following conditional expression is satisfied: where β2