The present invention relates to an electron energy loss spectrometer comprising a direct detection sensor, a high speed shutter and a sensor processor, wherein the sensor processor is configured to combine an image from a single sensor reading into one and convert a two-dimensional image from the sensor into a one-dimensional spectrum,and the one-dimensional spectrum is output to a computer in which the operation of the high-speed shutter is combined with the time at which the sensor is imaged; the shutter is controlled so as to allow exposure to an image corresponding to a single sensor reading.Exposing a plurality of images by imaging in an incomplete exposure, wherein the plurality of images are combined to form a composite image. The plurality of images are composed of images formed by exposing the sensors at different exposure times.