  We present a systematic comparison of different approaches for the modeling
of $t\bar{t}\gamma$ final states with leptonic decays at the LHC. On the one
hand, we consider a complete calculation at NLO QCD accuracy which includes all
resonant and non-resonant diagrams. On the other hand, we consider predictions
in the narrow-width approximation with top quark decays modeled at various
accuracies. In this way we quantify the impact of the off-shell effects in
$t\bar{t}\gamma$ production. We also discuss the relative importance of
double-, single- and non-resonant contributions in the complete calculation.
Finally we investigate the fraction of isolated photons from decays of top
quarks, which represent a background for measurements of anomalous $t\gamma$
couplings.
