To observe the behaviour of materials subject to impact shock loads, accurate high frequency measurements are vital. The measurement of ultra short pulses (less than 50 microseconds) can be carried out by means of electrical resistance strain guages (ERSGs) . The ERSG's also pick up electromagnetic interference signals. Dynamic photoelasticity was used as a check for the ERSG records. Dynamic photoelastic tests were carried out using a Barr and Stroud CP5 high speed rotating mirror camera. The timing of the event and illumination was critical. Important confirmatory results were obtained by this technique.