  We demonstrate that the corrections to the classical Kelvin image theory due
to finite electron screening length $\lambda$, recently discussed by Roulet and
Saint Jean, Am. J. Phys. 68(4) 319, is amenable to an exact closed form
solution in terms of an integral involving Bessel functions. An improper choice
of boundary conditions is rectified as well, enabling also a complete solution
for all potentials - both inside and outside the metal surface.
