| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a telephoto zoom lens in which a diagonal angle of view is 5 degrees or less particularly at a telephoto end and a zoom ratio is 3.75 times or higher, the zoom lens being configured such that while high imaging performance is held, a reduction in the entire length of an optical system, a reduction in the amount of movement of each lens group, reductions in the weight of a focus lens group and an amount of its movement, and a reduction of the size of a lens barrel can be achieved. <P>SOLUTION: The telephoto zoom lens comprises in order from an object side a positive first lens group, a negative second lens group, a positive third lens group, a positive fourth lens group and a negative fifth lens group. When varying power from a wide-angle end to a telephoto end, the interval between the first and second lens groups increases and the interval between the third and fourth lens groups and the interval between the fourth and fifth lens groups decrease. The fifth lens group comprises a 5a-th lens group of negative refractive power and a 5b-th lens group of negative refractive power. When focusing from an infinity distance focus state to a close-distance, the 5a-th lens group moves from the object side toward an image side along an optical axis and satisfies a predetermined condition. <P>COPYRIGHT: (C)2012,JPO&INPIT |
