ZOOM LENS

Japanese Patent JPH04294311

A

PURPOSE:To obtain a zoom lens with high optical performance of a power variation ratio of 8 and an F number of about 2 by providing three lens groups on the whole, and property setting the movement conditions, refracting power, etc., of the respective lens groups at the time of varying power. CONSTITUTION:The zoom lens consists of a 1st group with positive refracting power, 2nd group with negative refracting power, and a 3rd group with positive refracting power in order from the object side. As the power is varied from the short-focus side to the long-focus side, said 1st group moves along a track which is convex to the object said, the 2nd group moves from the object side to the image side, and the 3rd group moves monotonously; and the 3rd group have a group 3a and an image-side group 3b arranged in order at a large air interval and satisfies the conditions of -0.3