Objective lens system for microscopes

An objective lens system for microscopes comprising a front lens group and a rear lens group, said front lens group consisting of a first positive lens component and a second negative meniscus lens component having a concave surface on the image side, and said rear lens group comprising at least two lens components including a cemented three element component, said rear lens group comprising a third cemented meniscus lens component having a concave surface on the object side and a fourth positive lens component, and said objective lens system satisfying the following conditions:

• ##EQU5## wherein the reference symbols r.sub.5 and r.sub.6 represent radii of curvature on the image side surface of the second lens component and the object side surface of the third lens component, the reference symbol .SIGMA.d/n designates total sum of ratios between thicknesses and refractive indices of the respective lens elements of the third lens component, the reference symbols .nu..sub.p and .nu..sub.n denote Abbe's numbers of the first lens component and the negative element of the second lens component in the front lens group, the reference symbols .nu..sub.p, and .nu..sub.n, represent Abbe's numbers of the positive lens element and negative lens element of the third lens component in the rear lens group and the reference symbol f designates focal length of the entire lens system as a whole.