Based on several years of research in the area of space instrumentation, I will endeavour to explain how the imaging sensors used in smartphones, speed cameras, night vision goggles and deep space astronomical telescopes work, starting with some basic semiconductor physics, and moving up through the process engineering and architecture differences between CCD and CMOS-APS sensors, a few tricks theindustry uses to keep improvements going in imaging sensors, how to measure sensor performance and de-mystify manufacturer specifications, and how to prove the particle nature of light using nothing but a logitech webcam.