Copying lens system

A copying lens system comprising, in succession from the object side, a first biconvex positive lens, a first biconcave negative lens, a diaphragm, a second biconcave negative lens identical to said first biconcave negative lens, and a second biconvex positive lens identical to said first biconvex positive lens, said system satisfying the following conditions:

• 0.298F <f.sub.1 <0.378F
• -0.41F <f.sub.2 <-0.312F
• 1.54<r.sub.2 /r.sub.3 <2.38
• 0.064<N.sub.1 -N.sub.2 <0.146
• where
• F:
• the focal length of the entire lens system
• f.sub.1 :
• the focal length of the first and second biconvex positive lenses
• f.sub.2 :
• the focal length of the first and second biconcave negative lenses
• r.sub.2 /r.sub.3 :
• the ratio of curvature radii of the adjacent surfaces of the biconvex positive lens and the biconcave negative lens
• N.sub.1 -N.sub.2 :
• difference between the refractive index of the biconvex positive lens and the refractive index of the biconcave negative lens