(relating chip illumination to scene illumination)

See these Notes on practical photometry, written based on work in the Pulsed-Bipolar imager project carried out at Synaptics, Foveon and National Semiconductor around 1997 and periodicaly updated.

There is a magic formula relating chip illumination to scene illumination explained (albeit very concisely) and the error that existed previously is now corrected (March 2017). These notes also explain photometry units: nits, candela, lumens, lux, and they relate incident illumination to luminance of a surface. They include a few actual measurement results comparing lux and nits, and a candle measurement.