Traditionally, the potential used for the study of the orbital structure of a bar is derived from a more or less realistic analytical mass distribution. Since the light distribution of real barred galaxies does not look like the mass distribution of the models (see [1]), we have directly computed the potential from CCD frames. We have applied our method on a sample of 17 early-type barred galaxies and, for one of them, we have computed orbits in its calculated potential.