Patent ID: 8693110

Claim:
A lens system having a plurality of lens groups each made up of at least one lens element, consisting of a first lens group, an aperture diaphragm, and a second lens group in order from an object side, wherein the first lens group has a configuration including a first lens element having positive power, a second lens element having positive power, and a third lens element having negative power in order from the object side, or a configuration including a first lens element having positive power, a second lens element having positive power, a third lens element having positive power, and a fourth lens element having negative power in order from the object side, one lens element as a focus lens in the second lens group is moved with respect to an image surface in focusing from an infinity focusing state to a close range focusing state, some of lens elements in the second lens group are moved in a direction perpendicular to an optical axis, and the lens system satisfies the following condition expression: 0.2< |fF/fO|< 3.0 (1) where fF: a focal distance of the focus lens, and fO: a synthetic focal distance of the lens elements moving in the direction perpendicular to the optical axis.