A summary is given of recent results of ellipsometric measurements on freely suspended films, between two and several hundred molecular layers thick, of 2-methylbutyl 4-alkanoyloxybiphenyl-4’-carboxylate liquid-crystal compounds showing smectic-A and ferroelectric smectic-C phases. The results concern in particular : the sign inversion of the spontaneous polarization in thin films, the thickness divergence of the surface-induced smectic-C order on approaching the bulk smectic-A - smectic-C transition in very thick films, and the behavior of the smectic-A - smectic-C surface transition in thin and thick films. Special attention is paid to new observations the origins of which are still to clarify.