PURPOSE: To improve the balance between the center and periphery of a lens and compensate chromatic aberration and comatic aberration by allowing optical elements of a lens formed of eight elements in four groups which are arranged as specified to meet specific requirements.

CONSTITUTION: The 1st lens group I of a concave meniscus lens which has surface distance d1 and the convex surface at an object side and a concave meniscus lens which has surface distance d2 and is cemented thereto, the 2nd lens group II of a concave meniscus lens which has surface distance d4, a refractive index n3, Abbe number ν3, radius r3 of curvature and a concave meniscus lens which has surface distance d9, the 3rd lens group III of two lens elements which have surface distance d5, radius r9 of curvature of the cemented surface, face distance d9, a refractive index n5, and an Abbe number ν5, and the 4th lens group IV of two lens elements are ar ranged symmetrically about a stop. When optical elements of those lenses meet requirements shown by inequalities IWV, the balance between the center and periphery is improved and chromatic aberration and comatic aberration are compensated excel lently. In the inequalities, n1 and nIV are refractive indexes of the lens groups I and IV, ν1 and νIV are Abbe numbers of the lens groups I and IV, and (f) is the focal length of the whole system.