Patent ID: 7715116

Claim:
A telephoto lens system comprises a positive first lens group, a positive second lens group, a diaphragm, a negative third lens group comprising a focusing lens group, and a positive fourth lens group, in this order from an object, wherein said positive first lens group comprises a positive first lens element, a positive second lens element, and a negative third lens element, in this order from the object; wherein said positive second lens group comprises a negative or positive fourth lens element and a positive or negative fifth lens element which are cemented to each other, in this order from the object; wherein said negative third lens group comprises a positive or negative sixth lens element and a negative or positive seventh lens element which are cemented to each other, in this order from the object; wherein said positive fourth lens group comprises one positive eighth lens element; wherein upon focusing on an object at infinity to an object at a closer distance, said negative third lens group is moved toward an image; and wherein said telephoto lens system satisfies the following conditions: 1.4 <f/f 1<1.8 2.4 <f/f 12<3.0 −5.5< f/f 3<−3.5 wherein f designates the focal length of said telephoto lens system; f 1 designates the focal length of said positive first lens group; f 12 designates the combined focal length of said positive first lens group and said positive second lens groups; and f 3 designates a focal length of said negative third lens group.