A moire method for dynamic in-plane displacement measurement is used with the purpose of studying carbon fiber/epoxy composite specimens under tensile dynamic load. The displacement field is measured with a random noise level of less than 0.3 ?m and by using a high-speed camera, a framing speed of 1 million frames/s is achieved. Cracks propagating at speeds of 2000 m/s have been observed. To evaluate strain accurately from the displacement fields, a calibration for distortion in the high-speed image converter camera must be made. A method to measure the variable magnifications in the different frame areas of the camera back is described.