| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a compact-sized large-diameter zoom lens with high optical performance ranging from a visible region to a near-infrared region. <P>SOLUTION: A zoom lens comprises a negative first lens group L1 and a positive second lens group L2. A diaphragm SP is disposed between the first lens group L1 and the second lens group L2. The second lens group L2 includes at least four lenses 4 to 7, or more. At least one lens surface of the lens 4 located closest to the object side among the four lenses is aspherical. At least one lens surface of the lens 7 located closest to the image side is aspherical. A lens surface of the third lens 6 from the object side, the lens surface being on the object side, is convex. The relations of 65<νd<SB POS="POST">22</SB>and R<SB POS="POST">22a</SB>/R<SB POS="POST">22b</SB><0 are satisfied whereνd<SB POS="POST">22</SB>is the Abbe number of the second lens 5 from the object side, R<SB POS="POST">22a</SB>is the radius of curvature of the lens surface on the object side, and R<SB POS="POST">22b</SB>is the radius of curvature of the lens surface on the image side. <P>COPYRIGHT: (C)2012,JPO&INPIT</p> |
