PURPOSE: To improve the aberration correction of a lens of around 65° angle of view having brightness of about F2.8 by forming the same into the 5-group constitution consisting of positive, negative, positive, positive and negative lenses successively from the object side and so constituting these as to satisfy specific conditions.

CONSTITUTION: This lens is formed into the 5-group constitution consisting of the 1st group L1 having a positive refracting power, the 2nd group L2 having a negative refracting power, the 3rd group L3 having a positive refracting power, the 4th group L4 having a positive refracting power and the 5th group L5 having a negative refracting power, wherein the object side end face and image side end face of the 1st group L, are both made convex to the object side, and the object side end face and image side end face of the 5th group L5 are both made concave to the object side and these are so constituted that the focal length (f) of the entire system, the refractive index N of each group, the radius Ra of curvature of the image side end face of the 2nd group, the air space Da between the 3rd group and the 4th group and the air space. Db between the 4th group and the 5th group satisfy the relation shown in the table.