| 摘要 |
PROBLEM TO BE SOLVED: To provide an extremely small zoom lens that is mounted in a digital camera, portable mobile, or the like, the zoom lens being designed such that optical performance is satisfactory, and not only the entire length of a lens system on an optical axis but also the size of the entire lens system are reduced. SOLUTION: The zoom lens includes, in order from the object side: a first group G<SB>1</SB>composed of a first lens L<SB>1</SB>that is a negative meniscus lens, the concave face of which is oriented in the direction of an image face; a second group G<SB>2</SB>composed of a second lens L<SB>2</SB>with positive refractive power; and a third group G<SB>3</SB>composed of a third lens L<SB>3</SB>and fourth lens L<SB>4</SB>with positive or negative refractive power. When zooming takes place from the wide angle end (W) to the telephoto end (T), the zoom lens moves the first group G<SB>1</SB>toward the image side as if it draws a projecting arc, and moves the second and third groups G<SB>2</SB>and G<SB>3</SB>linearly toward the object side. The zoom lens satisfies (1) fw/f<SB>3</SB>≥-0.6, and (2) 0<R<SB>1</SB>/fw<10, wherein fw represents the composite focal distance of the entire lens system at the wide angle end, f<SB>3</SB>represents the focal distance of a third lens L<SB>3</SB>, and R<SB>1</SB>represents the curvature radius of the object side face of the first lens L<SB>1</SB>. COPYRIGHT: (C)2008,JPO&INPIT
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