Da Vinci experimented with the camera obscura and wrote an accurate scientific description of it, preparing the way for the men who were to make the machine a practical medium. Vasari in his famous Life of Leonardo points out that he gave his attention to mirrors and learned how they operated and how images were formed. But more important than this, he studied the human eye and was the first to explain it accurately, using the camera as his model, and in this way he really learned the fundamentals of its functional principles. To this day the camera is explained in simplest terms as a mechanical eye and the human eye is explained as a marvelous, natural camera. Da Vinci also noted the effects of visible impressions on the eye.
Roger Bacon was undoubtedly Leonardo’s master in optics and this is a definite link in the chain of the growing knowledge of light and shadow and of devices which would create illusions for instruction and entertainment. It has been pointed out that Leonardo and Roger Bacon had much in common—both being so far ahead of their own times that they were not understood until centuries later. And both men believed passionately in scientific research and investigation. As an example, Leonardo would spend hours, days or even weeks studying a muscle of an animal appearing in the background of a painting so that it could be drawn perfectly. As a concrete link with Bacon, Leonardo described a mirror camera device which made it possible for people on the inside to see the passerby in the street outside. Bacon, you may recall, achieved and described a similar effect.
Within two years after da Vinci’s death two other Italians, Maurolico and Cesariano, advanced the magic shadow art-science by writing scientific and experimental discussions of the subject. Somewhat later another Italian, Cardano, made another contribution.
Francesco Maurolico (Maurolycus), 1494–1575, a mathematician of Messina, and the great astronomer of his day, wrote De Subtilitate, about 1520, in which Pliny, Albertus Magnus, and Leonardo da Vinci are mentioned. The material included a mathematical, rather than experimental, discussion of light, mirrors and light theatres. This last subject shows that the use of light and shadow for theatrical purposes was being rapidly advanced. In 1521, Maurolico was said to have finished Theoremata de lumine et umbra ad perspectivam et radiorum incidentiam facientia, which was published in 1611 at Naples and in 1613 at Leyden. This book explained how a compound microscope could be fashioned. Men were now learning how to use lenses and how to make better ones so necessary for satisfactory projection of images.
Ars Magna Lucis et Umbrae, 1646
BURNING GLASSES of Archimedes were ancient optical devices. They were used in the defense of Syracuse in 212 B. C. Some type of glass or lens is required in every camera or projector.
Proposition 20 of the book was entitled “An object’s shadow can be converted and projected.” The author pointed out that if an object between a light and an opening is moved one way its shadow appears to move the other. He then went on to explain the reasons for Aristotle’s square hole and round sun. He also showed accurately the relation of images and objects which was fundamental for understanding how to focus lenses and mirrors.
Self portrait. Royal Palace, Turin