| 摘要 |
PROBLEM TO BE SOLVED: To provide a compact and large-diameter zoom lens which has a desired aperture ratio of approximately 2.8 and is readily built into a camera shake correction mechanism. SOLUTION: The large-diameter zoom lens has a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having positive refractive power, all arranged sequentially in this order, starting from the object side. When the magnification from the wide angle end to the telescopic end is changed the first lens group and the second lens group move apart from each other; the second lens group and the third lens group move closer to each other; the third lens group and the fourth lens group move closer to each other; the third lens group consists of a third front group having positive refractive power and a third rear group having negative refractive power, arranged sequentially in this order, starting from the object side; and when there are camera shakes, the image plane is corrected by moving only the third rear group in a direction perpendicularly crossing the optical axis, and the fourth lens group has a concave lens closest to the object side. COPYRIGHT: (C)2011,JPO&INPIT |
