Telephoto lens system

Abstract

A telephoto lens system including a first lens group having a positive refractive power and including at least three positive lenses and one negative lens; a second lens group having a negative refractive power and for performing focusing by moving along an optical axis; and a third lens group having a positive refractive power and including a 3a sub-lens group with positive refractive power and a 3b sub-lens group), wherein the 3a sub-lens group includes a negative lens and a positive lens sequentially arranged from an object side d, the 3b sub-lens group includes a positive lens and a negative lens sequentially arranged from the object side, and the telephoto lens system satisfies a condition, 0.17<fb/f<0.35, where, fb indicates a back focal length in air without a filter, that is, a distance from a lens surface of the telephoto lens system closest to the image side to an imaging surface with respect to the telephoto lens system having an optical arrangement at an infinite object position in air without the filter, and f indicates an overall focal length of the telephoto lens system.

Dependencies are inferred from the claim text.