[en] Imprisonment of resonance radiation by atomic absorption of Mn and Zn at 4030.76A and 2138.56A respectively, for a wide range of concentrations between 1 and 5x10³ppm in an air-acetylene flame has been investigated. The optical depths tau₀-bar, the mean probability values of photon escape theta, and photon capture tau are determined. It is shown that there is certain state of equilibrium between photon escape and capture, where tau₀-bar=1, and theta=tau=0.5 which were relevant to 50% of total absorption. The dependence of both tau₀-bar and tau on the total number of atoms in ground state Ncm^-3 has been found significant. It is found that imprisonment of resonance radiation is negligible at low absorber opacity (tau₀-bar<1), while is remarkable at high absorber opacities (tau₀-bar>1), and is independent on N at tau₀-bar>>1. The significance of imprisonment concept is carefully assessed. (author)