34 in the case of magnetic video tapes the interferometric measurement described above is used to determine the number of defects having a height of 1 micron or more per square centimeter of surface finally another value which characterizes the films containing fillers is the one which measures their haze the measurement of this haze is carried out according to astm standard d 1003 the haze of the films containing titanium oxide as a filler is generally too high for the waste from these films to be recovered in particular if this waste must be recycled into films for use in packaging an indirect advantage of the films according to the invention is that it is possible if desired to reduce their overall proportion of fillers and consequently to substantially reduce the value of the haze without thereby increasing the coefficient of friction to a prohibitive extent films containing fillers can thus be obtained which have a haze compatible with recycling of the waste if desired another object of the present invention is to use the biaxially drawn polyester films containing fillers described above for the preparation of magnetic tapes these tapes can be used in particular for recording sound audio tapes images video tapes or various other data computer tapes these magnetic tapes are obtained by coating the polyester films with layers of metal compounds appropriate to the various intended uses the present invention also envisages magnetic tapes manufactured in this manner from the polyester films containing kaolinite and titanium oxide as fillers finally the films according to the invention can also be used as dielectric layers in capacitors in order to.