In this paper, after a short recall of the information that can be extracted from different experiments based on the photoconductivity properties of a semiconductor, we present experimental results obtained on a thin film of hydrogenated amorphous silicon in the as-deposited, light-soaked and annealed states. We show that, taking advantage of the apparent discrepancies between the results of dc photoconductivity and modulated photoconductivity, density of states distributions as well as some of their capture coefficients can be deduced. The evolution of these quantities with light-soaking and annealing is also shown. The experimental results are also illustrated by means of numerical simulations.