A new method is described for obtaining the characteristic curves of photographic emulsions upon exposure to very short-time light pulses generated by a laser device. The method permits the measurement of reciprocity failure data for a range of very short exposure times (2 x 10(-8)-5 x 10(-6) sec) and further offers the possibility of studying intermittency effects for very short intermittency periods. Characteristic and reciprocity curves of unsensitized silver bromide and silver iodobromide emulsions with cubic and octahedral grains were determined by this method.