Abstract: A lens sequentially comprises, from an object side to an image surface: a first lens having negative focal power, an object side surface of the first lens being convex, and an image side surface of the first lens being concave; a second lens having positive focal power, an image side surface of the second lens being convex; a diaphragm; a third lens having positive focal power, an object side surface and an image side surface of the third lens both convex; a fourth lens having positive focal power, an object side surface and an image side surface of the fourth lens both convex; and a fifth lens having negative focal power, an object side surface of the fifth lens being concave, an image side surface of the fifth lens being convex, the fourth lens and the fifth lens constituting a cemented lens.