A zoom lens system for forming an optical image of a subject on the
image-sensing surface of an image sensor includes at least, from the
object side thereof, a first lens unit having a negative optical power
and a second lens unit having a positive optical power, and achieves
zooming by varying the distances between the individual lens units in
such a way that, during zooming from the wide-angle end to the telephoto
end, the distance between the first and second lens units decreases. The
first lens unit consists of two plastic lens elements.