PURPOSE: To obtain a wide viewing angle and to compensate chromatic aberration by using a lens material of the small difference of dispersion by specifying the constitution of a first lens to a third lens.

CONSTITUTION: This lens is composed of two and more kinds of lens materials, the differences of dispersion of the respective lens materials are smaller than 0.0055, in order from the object side, a first lens group L1, L2 composed of two and more lenses and a first to a third lenses of positive, negative and positive are arranged along the optical axis, a second lens group L3-L5 having positive focal distances and a third lens group L5, L7 composed of one and more lenses are arranged along the optical axis, a first and a second lenses, the second and a third lenses composing the second lens group L3-L5 are composed of lens materials having different dispersions from each other and conditions shown by the relations I-VI are satisfied. In the relations I-VI, F is the focal distance of the whole system, F1-F3 are the focal distances of the first to the third lens groups L6-L7 and f1-f3 are the focal distances of the first to the third lenses composing the second lens group L3-L5.