 Reciprocity also breaks down at extremely high levels of illumination with very short exposures.This is a concern for scientific and technical photography, but rarely to general photographers, as exposures significantly shorter than a millisecond are only required for subjects such as explosions and in particle physics, or when taking high-speed motion pictures with very high shutter speeds (1/10,000 sec or faster).In response to astronomical observations of low intensity reciprocity failure, Karl Schwarzschild wrote (circa 1900)