PURPOSE: To obtain a retrofocusing type lens of rear group let out system with large aperture and large angle of field and small fluctuation in spherical aberration, astigmatism and comatic aberration by employing two-group lens constitution and satisfying a specific condition.

CONSTITUTION: This lens is equipped with a first lens group G1 fixed when focusing is obtained and with negative refracting power, and a second lens group G2 moved when the focusing is obtained and with positive refracting power. The first lens group G1 comprises a wide converter. The second lens group G2 comprises a master part. The following conditions can be satisfied; 2≤-f1/f0≤9, and 0<f2B/f2A<0.9. Where, the focal length of the first lens group G1 is assumed as f1, the focal distance of the whole lens system as f0, the synthetic focal length of a second lens group first unit G21 and a second lens group second unit G22 as f2A, and the synthetic focal length of a second lens group third unit G23 and a second lens group fourth unit G24 as f2B.