Patent ID: 6429978
Filing Date: 2002-08-06
Classification: G02B

Abstract:
A zoom lens comprising from the object side:a first lens unit of negative refractive power; a second lens unit of positive refractive power; a third lens unit of positive refractive power; and a fourth lens unit of negative refractive power, wherein a zooming operation is performed by axially moving the lens units so that the spacing between the first lens unit and the second lens unit becomes wider at the telephoto end than at the wide-angle end, the spacing between the second lens unit and the third lens unit becomes wider at the telephoto end than at the wide-angle end, the spacing between the third lens unit and the fourth lens unit becomes narrower at the telephoto end than at the wide-angle end, and wherein the following conditions hold: 1.0<F12w/Fw<2.5 0.6<F3/Fw<1.3 0.4F4/Fw|<0.7 0.01F2/F1|<0.16 where Fw represents the focal length of the entire lens system at the wide-angle end, Fi represents the focal length of an i-th lens unit, and F12w represents the composite focal length of the first lens unit and the second lens unit at the wide-angle end.