The disclosure provides multimode configurable spectrometers, a method of operating a multimode configurable spectrometer, and an optical monitoring system. In one embodiment the multimode configurable spectrometer includes: (1) an optical sensor configured to receive an optical input and convert the optical input to electrical signals, wherein the optical sensor includes multiple active pixel regions for converting the optical input to the electrical signals, and (2) conversion circuitry, having multiple selectable converting circuits, that is configured to receive and convert the electrical signals to a digital output according to a selected one of the selectable converting circuits.