“The German astronomer Johannes Kepler coined the term “camera obscura” in the early seventeenth century, but by then the phenomenon had been known for millennia; in fact, it is perhaps the oldest known optical illusion. Some form of camera obscura was most likely behind a popular illusion performed in ancient Greece and Rome, in which spectral images were cast upon the smoke of burning incense by performers using concave metal mirrors – hence the expression “smoke and mirrors.”
