The Andor iXon3 860 back-illuminated EMCCD is designed for very rapid imaging of low light events, combining > 500 frames/sec with single photon detection capability. UltraVac^TM vacuum technology provides absolute protection of the back-illuminated sensor, ensuring performance longevity. Thermoelectric cooling down to -100˚C minimizes EM-amplified darkcurrent, whereas industry fastest vertical shift speeds minimizes both clock induced charge noise and vertical smear during frame transfer. Sub-millisecond biology is readily accessible through use of sub-array selection and pixel binning.