PURPOSE: To keep a satiafactory performance up to short distance photographing by constituting a lens system of four groups and satisfying specific conditions.

CONSTITUTION: This lens system consists of a lens group I which consists of three partial groups, namely, a lens group I-1 having a position refractive index, a lens group I-2 having a negative refractive index, and a lens group I-3 having a positive index and has a positive refractive index, a lens group II having a negative refractive index, a lens group III having a positive refractive index, and a lens group IV having a positive refractive index in order from the object side and satisfies conditions of inequalities where fI, d(I-1,I-2), hI-1, hI-2, and f(I-1,I-2) are the focal length of the whole of the system in the long focus distance end, the interval between lens groups I-1 and I-2, the height of paraxial incidence on the lens group I-1 of paraxial rays incident from an object in the infinity, the height of paraxial incidence on the lens group I-2 of paraxial rays incident from the object in the infinity, and the resultant focal length of lens groups I-1 and I-2 respectively. Thus, a high optical performance is kept up to close range photographing.