A rear focus zoom lens is disclosed that includes, in order from the object side:
a first lens group having positive refractive power; a second lens group having
negative refractive power; a third lens group having positive refractive power
and including a stop; a fourth lens group having negative refractive power; and
a fifth lens group having positive refractive power. The second lens group and
the third lens group are moved along the optical axis for zooming, the fourth lens
group is moved along the optical axis for focusing, and the fourth lens group comprises
a doublet consisting of a negative lens element and a positive lens element. The
fifth lens group may have a specified configuration which includes an aspherical
surface and that satisfies a specified condition which insures that aberrations
are satisfactorily corrected over the entire range of zoom.