  The kinematical effect induced by the transversal motion of a gravitational
lens on the frequency shift of light has been investigated in detail, while the
effect of the radial motion is thought to be much smaller than the transversal
one and thus has usually been neglected. In this work, we find that the radial
velocity effect on the frequency shift has the same order of magnitude as that
of the transversal velocity effect, when the light emitter (or the receiver) is
close to the gravitational lens with the distance between them being an impact
parameter scale. The significant velocity effect is usually transient due to
the motion of the gravitational lens relative to the light emitter or the
receiver.
