A detailed and rather technical explanation of how the camera system works was given by Kepler. Towards the end of the description he wrote an important instruction: “All the walls of the camera except the one used as the screen for the images should be black.” This was necessary to prevent reflection and dulling of the brilliance of the images on the white wall or screen. Everyone knows how the insides of a modern camera are black for the very same purpose. Kepler also noted that the “camera” must be tightly sealed. He was the first to refer to the device under the simple name of “camera” which in time was adopted universally. Kepler also was the first to give a sound theory of vision. (Recall the shot-from-eye or shot-from-object schools of the ancients.) Kepler stated, “Seeing amounts to feeling the stimulus of the retina which is painted with colored rays of the visible world. The picture must then be transmitted to the brain by a mental current and delivered at the seat of the visual faculty.” That is a rather good definition even by modern standards. Kepler, however, was not 100 per cent correct. He held that light had an infinite velocity. To Kepler goes the credit for being the first correctly to explain after-images, a knowledge of which is so vital to understanding how the illusion of motion is created. Kepler started to use a telescope about 1609 and through its use he was able to develop improved ideas for the room camera by the time he published his _Dioptrice_, “Concerning Lenses,” a foundation of modern optics, in 1611. In that work the basis was first established for what was later to be long-range or “telescope” photography which makes possible many important effects in the modern motion picture. The telescope, the most highly developed lens system and the reverse of a projection arrangement, was invented in Holland in the early part of the 17th century. Galileo, who with Kepler did much to popularize the telescope, admitted that he had seen one made by a Dutchman before he fashioned his own. The name “telescope” was coined by Damiscian of the Italian scientific “Academy of the Lynxes,” to which Porta also had belonged. The invention of the telescope is commonly credited to “the spectacle maker of Middleburgh,” usually identified as Hans Lippershey. The compound microscope, effects of which had been indicated by Roger Bacon, evidently also was invented a few years prior to the telescope--by Zachary Janssen, in Holland. But it was first described in Italy. Early telescopes generally followed the model developed by Galileo, while by the middle of the 17th century the superiority of Kepler’s method was recognized and larger and more powerful telescopes were possible. In recent times the telescope has reverted to a mirror--or Burning Glass--reflecting system instead of the standard style refracting telescope.