Patent ID: 6333824
Filing Date: 2001-12-25
Classification: G02B

Abstract:
A zoom lens system consisting, in order from the object side, of:a first lens unit having a positive refractive power; anda second lens unit having a negative refractive power; and configured to change a magnification from a wide position to a teleposition by moving the lens units toward the object side so as to narrow an airspace reserved between the first lens unit and the second lens unit,wherein said first lens unit consists, in order from the object side, of a first negative subunit and a second positive subunit,wherein the first negative subunit of said first lens unit comprises, in order from the object side, a biconcave lens component having a radius of curvature on the image side which is smaller than that on the object side and a negative meniscus lens component having a convex surface on the object side,wherein said second positive subunit of said first lens unit comprises a positive lens component and a negative lens component,wherein said second lens unit consists, in order from the object side, a positive lens component and a negative lens component, andwherein said zoom lens system satisfies the following conditions (1), (2) and (3):0.2<.vertline.f.sub.G11 /D.vertline.<1.8 (1).nu..sub.L4 <50 (2)50<.nu..sub.L5 <70 (3)wherein the reference symbol f.sub.G11 represents a focal length of the first negative subunit G11 of the first lens unit G1, the reference symbol D designates a diagonal length of an image surface, the reference symbol .nu..sub.L4 denotes an Abbe's number of the positive lens component L4 of the second lens unit G2 and the reference symbol .nu..sub.L5 represents an Abbe's number of the negative lens component L5 of the second lens unit G2.