Patent ID: 6639721
Filing Date: 2003-10-28
Classification: G02B

Abstract:
A zoom lens system comprising, in order from an object side:a first lens unit of negative refractive power, a second lens unit of positive refractive power, a third lens unit of negative refractive power, and a fourth lens unit of positive refractive power, wherein said zoom lens system zooming from a wide-angle end to a telephoto end while varying a separation between each lens units so that conditional expressions D1W>D1T D2W2T, and D3W>D3T are satisfied where DiW is a separation between i-th and (i+1)-th lens units at a wide-anile end, DiT is a separation between the i-th and (i+1)-th lens units at a telephoto end, and wherein a diffraction optical element is included in the fourth lens unit, and a conditional expression 154DOE /ft<1500 is satisfied where f4DOE is a focal length of only a diffraction component of the diffraction optical element, and ft is a focal length of an entire lens system at the telephoto end.