Patent ID: 7450314
Filing Date: 2008-11-11
Classification: G02B

Abstract:
1. A zoom lens system comprising, in order from an object side: a first lens unit having a positive refractive power; a second lens unit having a negative refractive power; a third lens unit having a positive refractive power; a fourth lens unit having a negative refractive power; and a fifth lens unit having a positive refractive power, wherein during magnification change from a wide-angle end to a telephoto end, each of spaces between the respective lens units changes; in the telephoto end as compared with the wide-angle end, the space between the first lens unit and the second lens unit increases, and the space between the second lens unit and the third lens unit decreases; and the first lens unit includes one lens component; the second lens unit includes a positive lens and a negative lens; and the total number of lenses constituting the first lens unit and the second lens unit is four or less, wherein the lens component is defined as a single lens or a combination of lenses which has only two air contact surfaces including an object-side surface and an image-side surface in an effective diameter; and wherein the first lens unit satisfies the following conditions: in which fl is a focal length of the first lens unit, fw is a focal length of the zoom lens system in the wide-angle end, and ft is a focal length of the zoom lens system in the telephoto end.