A new class of video rate imagers based on back-illuminated and thinned CCDs is available that shows promise to replace conventional image intensifiers for most military, industrial, and scientific applications. Thinned, back-illuminated CCDs (BCCDs) and electron-bombardment CCDs (EBCCDs) offer low light level performance superior to conventional image intensifier coupled CCD (ICCD) approaches. These new, high performance devices promise to expand the fields of science, provide high contrast, high resolution, low light level surveillance imaging, and make nighttime pilotage safer for military aviators. This paper presents experimental data which illustrates how responsivity, gain, and modulation transfer function (MTF) determine the low light imaging capability, the 'target of interest' signal to noise ratio (SNR) of each of these types of sensors. High SNR and MTF make BCCDs the imager of choice under moderately low light levels and EBCCDs the imager of choice under extremely low light level conditions.