Total photofission cross sections for ${}^{238}\mathrm{U}$, ${}^{235}\mathrm{U}$, ${}^{233}\mathrm{U}$, ${}^{237}\mathrm{Np}$, ${}^{232}\mathrm{Th}$, and ${}^{\mathrm{nat}}\mathrm{Pb}$ have been measured simultaneously, using tagged photons in the energy range ${E}_{\ensuremath{\gamma}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.17--3.84\mathrm{GeV}$. This was the first experiment performed using the Photon Tagging Facility in Hall B at Jefferson Lab. Our results show that the photofission cross section for ${}^{238}\mathrm{U}$ relative to that for ${}^{237}\mathrm{Np}$ is about $80%$ over the entire energy range, implying the presence of important processes which compete with fission. If we assume that for ${}^{237}\mathrm{Np}$ the photofission probability is equal to unity, we observe a significant shadowing effect, starting below 1.5 GeV.