| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-performance zoom lens system that has a remarkably reduced overall length of a lens and hence a reduced size, and has good balance between a wide view angle at a wide-angle limit and a high zooming ratio, and to provide an imaging device and a camera. SOLUTION: The zoom lens system comprises, in order from an object side to an image side, a first lens group having positive power, a second lens group having negative power, a third lens group having positive power, and a fourth lens group having positive power, wherein in zooming from a wide-angle limit to a telephoto limit, the first to the fourth lens groups are moved respectively along an optical axis so that the air spaces between the respective lens groups should vary, to achieve magnification change, and wherein the conditions: -0.60<M<SB>2</SB>/f<SB>G2</SB><-0.07,ω<SB>W</SB>≥30 and f<SB>T</SB>/f<SB>W</SB>≥4.5 (M<SB>2</SB>is an amount of axial movement of the second lens group in the optical axis in zooming from the wide-angle limit to the telephoto limit, f<SB>G2</SB>is a composite focal length of the second lens group,ω<SB>W</SB>is a half view angle at the wide-angle limit, and f<SB>T</SB>and f<SB>W</SB>are focal lengths of the entire system at the telephoto limit and at the wide-angle limit, respectively) are satisfied. The zoom lens system, the imaging device and the camera are provided. COPYRIGHT: (C)2011,JPO&INPIT |
