Elastic scattering of 180 MeV antiprotons by C, 16O, 18O and Ca and of 47 MeV antiprotons by Ca is analyzed with the help of an optical model. Model-independent Fourier-Bessel (FB) description of the potential leads to excellent fits to the data and clearly shows that the potential is well-defined only at the extreme surface region. Simple density-independent folding model approach leads to equally good fits and to full consistency with the FB potentials. The information content of the data regarding the optical potential is discussed.