Patent ID: 6014268
Filing Date: 2000-01-11
Classification: G02B

Abstract:
A zoom lens comprising, in order from a photographic object side:a first lens group having a negative refractive power;a second lens group having a positive refractive power;said first lens group including the following adjacent lens elements, in order from the photographic object side,a first lens element having a meniscus shape and negative refractive power with its convex surface on the photographic object side, said first lens element being the most object-side lens element of said zoom lens and including a surface which is aspherical,a second lens element having a meniscus shape and negative refractive power with its convex surface on the photographic object side; anda third lens element which has a positive refractive power and a meniscus shape with its convex surface facing the photographic object side;whereinthe overall focal length of the zoom lens is varied by varying the spacing between said first lens group and said second lens group, andsaid second lens group comprising, on the most object-side of said second lens group, a fourth lens element of positive refractive power, said fourth lens element satisfying the following equation:.vertline.R.sub.4F /R.sub.4R .vertline.=1.0whereinR.sub.4F and R.sub.4R respectively represent the radius of curvature of the object-side surface and the radius of curvature of the image-side surface of said fourth lens element.