Studying the antiferromagnetic phase of the Hubbard model by dynamical mean-field theory, we observe striking differences with static (Hartree-Fock) mean field: The Slater band is strongly renormalized and spectral weight is transferred to spin-polaron sidebands. Already for intermediate values of the interaction U the overall bandwidth is larger than in the Hartree-Fock mean field and the gap is considerably smaller. Such differences survive any renormalization of U. Our photoemission experiments for Cr-doped V(2)O(3) show spectra qualitatively well described by dynamical mean-field theory.