  We analyze the frequency shift of photons propagating on an asymptotically
flat spacetime describing a collapsing, spherical dust cloud. We focus on the
case where the interaction of the photons with the matter can be neglected.
Under fairly general assumptions on the initial data characterizing the
collapse, we show that photons with zero angular momentum which travel from
past to future null infinity, crossing the collapsing cloud through its center,
are always redshifted with respect to stationary observers. We compute this
redshift as a function of proper time of a distant stationary observer and
discuss its dependency on the mass distribution of the cloud. Possible
implications of this redshift effect for weak cosmic censorship and light
propagation in cosmological spacetimes are also briefly discussed.
