| 摘要 |
PURPOSE:To obtain a high-aperture ratio zoom lens which has aberrations corrected well, by changing the air gap between the first and second lens groups in the lens system, consisting of two groups, namely, negative and positive lenses which are arranged in order from the object side to perform zooming and forming one lens face, at least, of each of both groups to an aspherical surface. CONSTITUTION:The air gap between the first groupIand the second group II in the lens system consisting of the negative lensIand the positive lens II which are arranged in order from the object side is changed to perform zooming, and one lens face, at least, of the first groupIand one lens face, at least, of the first or second lens of the second group are formed to aspherical surfaces. By providing the aspherical surface in the object side from the center of the first groupI, various aberrations in the telephoto side are not affected much, and the fluctuation of various aberrations due to zooming is held well, and the barrel form distortion in the wide angle side is corrected. By providing the aspherical surface in the second group II, the spherical aberration is corrected. Thus, a high-aperture ratio zoom lens which has aberrations corrected well is obtained. |
