A zoom lens which suppresses variations of an exit pupil and is telecentric on
the image side in the whole range of zooming comprises, from the object side toward
the image side: a first negative in optical power, an aperture stop, a second lens
unit positive in optical power and a third lens unit positive in optical power.
In zooming from the wide angle end to telephoto end, the distance between the first
lens unit and the aperture stop narrows, the between the aperture stop and the
second lens unit narrows, and the between the second lens unit and the third lens
unit widens; and the condition: 0(Dw-Dt)/fw1
is satisfied, where is the distance between aperture stop and the second lens unit
at the wide angle end is Dw, at the telephoto end is Dt and
the focal length at the wide angle end fw.
