Patent Number: 7,102,830

Title: Electronic imaging system

Abstract: The invention has for its object to use a zoom system that comprises a reduced number of lens elements, is compact and simplified, and has high image-formation capability, thereby achieving thorough size reductions in video cameras or digital cameras. A zoom lens for use on an electronic imaging system comprises a negative first lens group G1, an aperture stop S, a positive second lens group G2 and a positive third lens group G3. Upon zooming from the wide-angle end to the telephoto end of the zoom lens, the second lens group G2 moves only toward the object side of the zoom lens and the third lens group G3 moves in a locus different from that of the second lens group G2. The second lens group G2 is made up of a positive first lens element having an aspheric surface on its object side, a negative second lens element, a positive third lens element and a negative fourth lens element. The first and second lens elements are cemented together, and the third lens group G3 moves independently for focusing. The second lens group G2 satisfies condition (1) with respect to the Abbe numbers of the third and fourth lens elements, condition (2) with respect to the shape of the third lens element, and condition (3) with respect to the composite focal length of the third and fourth lens elements.

Inventors: Mihara; Shinichi (Tama, JP)

Assignee: Olympus Corporation

International Classification: G02B 15/14 (20060101)

Expiration Date: 9/05/02018