Lens system for a copier

Claim 1

A lens system having a six group and eight element structure, comprising, in the order mentioned from an object side: a first group including a first lens which is a double-convex lens; a second group including a second lens which is a double-concave lens; a third group including a third lens which is a concave meniscus lens arranged with its convex surface directed to the object side and a fourth lens which is a convex meniscus lens cemented to said third lens and arranged with its convex surface directed to the object side; a stop; a fourth group including a fifth lens which is a convex meniscus lens identical to said fourth lens and arranged with its concave surface directed to the object side and a six lens which is a concave meniscus lens identical to said third lens and cemented to said fifth lens with its concave surface directed to the object side; a fifth group including a seventh lens which is a double-concave lens identical to said second lens; and a sixth group including a eighth lens which is a double-convex lens identical to said first lens; whereby the conditions of 0.05 < |f 3.4 /f 1.2 | < 0.27; 10 < ν₄ - ν₃ < 30; and n₁ > 1.67; are satisfied; where, f 1.2 : combined focal distance for the first (sixth) and second (fifth) groups; f 3.4 : combined focal distance for the third (fourth) group; ν₃ : Abbe number of the third (sixth) lens; ν₄ : Abbe number of the fourth (fifth) lens; and n₁ : Refractive index of the first (eighth) lens.