The Axis-Photonique PX1 fast X-ray streak camera records the temporal structure of events with picosecond accuracy. Using a potassium iodide photocathode the streak camera has been characterised for the effects of space charge. In a recent grazing incidence pumping X-ray laser experiment the streak camera was coupled to the output of a flat field spectrometer to observe first order diffraction. The second order was observed using a CCD camera. In this paper data is presented from this experiment comparing the brightness of the X-ray laser emission with the dispersion of the streaked image both temporally and spectrally (non temporal direction). Consequently measurements of the dynamic range of the streak camera are made. The results are compared with data from previous experiments.