Copy lens

A copy lens comprising four lens elements, which are arranged symmetrically with an aperture in order from the object end to the image end, said four lens elements including a first biconvex element and a biconcave element, which are positioned on one side of said aperture, a third biconcave element identical with said second biconcave element and a fourth biconvex element identical with said first biconvex element, which are positioned on the other side of said aperture, and satisfying the following conditions:

• -0.5<R1/R2<-0.28;
• 1.4<R2/R3<2.4;
• 0.022<d4/f<0.036;
• 1.85<N.sub.1 -.nu..sub.1 /216<1.91;
• and
• 0.05<F.multidot.d3/f<0.2
• where
• f is the overall focal length of said copy lens;
• R1 is the radius of an object side surface of said first element;
• R2 is the radius of an image side surface of said second element;
• R3 is the radius of an object side surface of said second element;
• d3 is the axial distance between surfaces of said second element;
• d4 is the axial distance between adjacent surfaces of said second and third elements;
• N.sub.1 is the index of refraction of said first element;
• .nu..sub.1 is the Abbe number of said first element;
• and
• F is the F number.