Viewfinder lens system

Claim 1

A viewfinder lens system comprising from an object side to an eye side; a first lens element having a negative refractive power; and a second lens element having an optical axis and a positive refractive power with an air space formed between the first and second lens elements, wherein the second lens element has an aspheric surface at its object side whose radius of curvature increases in accordance with an increase in height from its optical axis; and the viewfinder lens system fulfills the following conditions; 0.4<R.sub.2 /f<1.2 0.35<R.sub.3 /R.sub.2 <0.8 -1.5<R.sub.4 /f<-0.5 -0.8<ε<0 25<ν.sub.1 <35 55<ν.sub.2 <65 wherein: R 2 represents a radius of curvature of an eye side surface in the first lens element; R 3 represents a paraxial radius of curvature of an object side surface in the second lens element; R 4 represents a radius of curvature of an eye side surface in the second lens element; f represents a focal length of the whole lens sytem; ν 1 represents an Abbe number of the first lens element; ν 2 represents an Abbe number of the second lens element; and ε represents an aspheric coefficient of the aspheric surface provided by ##EQU5## wherein, X represents a distance, measured along a direction parallel with the optical axis, from a center of the aspheric surface to a point on the aspheric surface at a height, Y, from the optical axis.