| 摘要 |
PURPOSE:To realize the high performance of a compact lens which has a >=2 zoom ratio and about 300mm. focal length on a telephoto side while chromatic aberration on a long focus side is improved, by using low dispersion glass in the 1st lens group. CONSTITUTION:This zoom lens system consists of the 1st lens group having positive refracting power, the 2nd lens group having negative refracting power, the 3rd lens group having positive refracting power, and the 4th lens group having negative refracting power successively from an object side. The 2nd lens group and 3rd lens group move independently of each other to perform variable magnification while an image plane position is held constant. For variable magnification from a wide side to a telephoto side, the 2nd lens group moves in one direction from an object to an image side, and is a lens group of a negative and a negative lens from the object side and a combined negative lens of a concavo- concave negative lens, a concavo-concave negative lens and a positive lens. The 3rd group moves in one opposite direction to the 2nd group and is a lens group of a positive, a positive, and a negative lens from the object side. Then, inequalititesI-VII. |
