Abstract A lens for reading an original has first to fifth lens groups sequentially arranged from an object side of a lens system to an image side thereof. The first lens group is constructed by a first lens composed of a negative meniscus lens having a convex face directed on the object side. The second lens group is constructed by a second lens composed of a positive lens. The third lens group is constructed by a third lens composed of a biconcave lens. The fourth lens group is constructed by a fourth lens composed of a positive lens. The fifth lens group is constructed by a fifth lens composed of a positive meniscus lens having a convex face directed on the object side. A combined focal length f of the entire lens system, a focal length f 1 of the first lens group, and a combined focal length f 24 of the second to fourth lens groups satisfy the following conditions. -2.4<(f.sub.1 /f)<-1.2 (I) 0.85<(f.sub.24 /f)<1.5 (II).
A lens for reading an original, comprising: first to fifth lens groups sequentially arranged from an object side of a lens system to an image side thereof; the first lens group being constructed by a first lens composed of a negative meniscus lens having a convex face directed on the object side; the second lens group being constructed by a second lens composed of a positive lens; the third lens group being constructed by a third lens composed of a biconcave lens; the fourth lens group being constructed by a fourth lens composed of a positive lens; and the fifth lens group being constructed by a fifth lens composed of a positive meniscus lens having a convex face directed on the object side; a combined focal length f of the entire lens system, a focal length f 1 of the first lens group, and a combined focal length f 24 of the second to fourth lens groups satisfying the following conditions, -2.4<(f.sub.1 /f)<-1.2 (I) 0.85<(f.sub.24 /f)<1.5 (II).
Claim 2
Dependent Claim
167 words
A lens for reading an original, comprising: first to fifth lens groups sequentially arranged from an object side of a lens system to an image side thereof; the first lens group being constructed by a first lens composed of a negative meniscus lens having a convex face directed on the object side; the second lens group being constructed by a second lens composed of a positive lens; the third lens group being constructed by a third lens composed of a biconcave lens; the fourth lens group being constructed by a fourth lens composed of a positive lens; and the fifth lens group being constructed by a fifth lens composed of a positive meniscus lens having a convex face directed on the object side; a combined focal length f of the entire lens system, a focal length f 1 of the first lens group, and a combined focal length f 24 of the second to fourth lens groups satisfying the following conditions, -2.4<(f.sub.1 /f)<-1.2 (I) 0.85<(f.sub.24 /f)<1.5 (II).
Claim 3
Dependent Claim
25 words
An original reading lens as claimed in claim 1, wherein the condition (I) is a condition for restricting refracting power of the first lens group.
Claim 4
Dependent Claim
39 words
An original reading lens as claimed in claim 1, wherein the condition (II) is a condition for setting refracting power of the second to fourth lens groups to be approximately equal to refracting power of the entire lens system.