A lens that can be used in a digital camera includes in sequence a first
lens element (20), a second lens element (30), a third lens element (40),
and a fourth lens element (50). The first lens element is biconvex, and
includes a first aspheric surface (22) and a second aspheric surface
(24). The second lens is biconcave, and includes a third aspheric surface
(32) and a fourth aspheric surface (34). The third lens element is
concavo-convex, and includes a fifth aspheric surface (42) and a sixth
aspheric surface (44). The fourth lens element includes a seventh
aspheric surface (52) and a eighth aspheric surface (54), the seventh
aspheric surface and the eighth aspheric surface being wavelike. All of
the lens elements are made from plastic. The lens is light, has strong
impact resistance, and provides good image quality.