  Results of relativistic calculations of the direct knockout (DKO) mechanism
for the photon induced removal of a proton from a target nucleus over a wide
range of energies and nuclei are presented. Spectroscopic factors used in the
calculations are fixed from consistent analyses of the quasifree electron
scattering process (e,e'p). The results indicate that within the uncertainties
of the model, the knockout contributions are generally close to the
experimental data for missing momenta below approximately 500 MeV/c. This is in
disagreement with nonrelativistic analyses which often find that the direct
knockout contribution can be quite small compared to the data and that meson
exchange corrections can be important. The present study suggests that meson
exchange current contributions may not be as large when treated in a
relativistic framework. We also point out some difficulties we encountered in
analyzing the data for a 12C target at photon energies below 80 MeV.
