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Zoom lens system

  • US 7,075,734 B2
  • Filed: 05/13/2005
  • Issued: 07/11/2006
  • Est. Priority Date: 12/25/2002
  • Status: Expired due to Term
First Claim
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1. A zoom lens system comprising, in order from an object:

  • a first lens group; and

    a second lens group;

    wherein when the state of lens group positions varies from a wide-angle end state to a telephoto end state;

    the first lens group and the second lens group are moved such thata distance between the first lens group and the second lens group varies; and

    wherein the second lens group is composed of four lenses or less;

    the second lens group includes a diffractive optical surface formed on a lens surface except the most object side lens surface; and

    the following conditional expression is satisfied;


    0.2<

    C/fw<

    2.0where C denotes the effective diameter of the diffractive optical surface, and fw denotes the focal length of the zoom lens system in the wide-angle end state.

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