| 摘要 |
PURPOSE:To obtain a zoom lens containing an area of a standard focal distance which has realized a large aperture ratio in the whole zoom range and also high performance, in case of executing zooming by changing an interval between both lens groups, by constituting it of 2 lens groups. CONSTITUTION:A titled zoom lens consists of the first lens group having negative refractive power and the second lens group having positive refractive power in order from an object side, and on the nearest part to the object side in the first lens group, a negative meniscus lens whose convex surface has been turned to the object side is provided, and on the nearest part to an image side, a positive meniscus lens whose convex surface has been turned to the object side is provided, the second lens groups consists of a positive lens and 3 positive meniscus lenses whose convex surface has been turned to the object side in order from the object side, at least 1 lens surface among these 4 positive lenses is provided with a combined surface of a divergence action, and at least 1 lens surface in the first lens group is formed aspherically. When a focal distance of the first lens group, a focal distance of the whole system in case when a telephoto end is in a zoom position, and a principal point interval between the first lens group and the second lens group in case when the telephoto end is in a zoom position are denoted as F1, Ft and Et, respectively, it is desirable to satisfy such as condition as 0.8<¦F1¦/Ft<1.2, 0.2<Et/Ft<0.45. |
