  We demonstrate cloaking with four lenses of different focal lengths. To
achieve this, we compute the separation distances between lenses such that the
effective ABCD matrix is equal to just a propagation in free space. Previously,
calculations using this method are restricted to 2 pairs of lenses with equal
focal lengths. Our computations, on the other hand, had no such restrictions:
we generalize even with an asymmetric case. We derive expressions that show the
dependence of the distances on the lenses and their focal lengths. Furthermore,
we propose a way to minimize the length of this cloak. Our equations reduce to
the Rochester cloak when its restriction is imposed. A general paraxial cloak
could be useful in advanced undergraduate experiments in optics because: 1) the
limit imposed by the focal length has been lifted; and 2) there is a
pedagogical benefit of doing experiments with lenses beyond the usual imaging
experiments such as reinforcing concepts in Gaussian optics.
