In my quest for a first entry and in homage to this blog’s name, I quickly settled upon Johannes Kepler as the subject as his path in life was altered by his observation of many astronomical events and a solar eclipse in particular. As he is a connection to my long lost studies in physics and math I was certainly aware of his contributions to science and humanity. However, in coming across the attached quotes and linked article I rediscovered with surprise and joy, the importance of those contributions to my life today.
Johannes Kepler - A Founding Father of Photography
Shedding some light! « The Renaissance Mathematicus
“Optics plays a major role in observational astronomy and it was from the context of observing a solar eclipse that Kepler developed his own interest in optics and the need to improve it. His investigations threw up a whole series of optical questions to which, in his own words, he could not find answers in the existing literature and so he set about investigating the questions for himself. … Kepler covers almost all aspects of optics and produces some very significant results in the process. Firstly he solves the so-called pinhole problem, which was one of his main reasons for starting his investigations. This problem is that the moon when projected through a small aperture such as that of a camera obscura during a solar eclipse appears smaller than at other times. This problem was known to both the Islamic and European optical experts in the Middle Ages but as Kepler had discovered none of them could explain why. This work also presented his inverse square law of the propagation of light, which is the first mathematical law of nature published in the early modern period. … Possibly Kepler’s greatest achievement in the Pars optica was to give the correct description of how the eye functions, namely as a form of camera obscura (a name invented by Kepler and the origin of the name of our photographic camera) in which the lens projects the image onto the retina which actually perceives the image. The major objection to this theory is that the projected image is inverted but we see the world the correct way up. Kepler countered this objection in a surprisingly modern way. He said that the brain is aware of what is up and what is down in the real world and corrects the inverted image delivered by the eye. At the end of his book Kepler makes some basic investigations of the optical properties of lenses and how they function together with the eye to correct defects in vision. This is historically interesting because convex lenses had been used in spectacles since about 1260 and concave ones since at least 1450 but Kepler’s optical analysis was the first ever published scientific investigation of how lenses function, something he would pick up on again eight years later in his second book on optics.”
“1608 saw the invention of the telescope and 1609 its first use in astronomy by various European scientists. The results of these early telescopic astronomical observations were called into doubt for various very good reasons. One of those reasons was the fact that there existed no scientific theory of how a telescope actually worked. … The man who supplied the missing theory was Kepler. Going back to his initial investigations on lenses in his Pars optica he produced a mathematical description of how each type of lens functions both singularly and in conjunction with the eye. He then moves on to combinations of lenses giving a complete mathematical description of the Dutch or Galilean telescope. Following this he then proceeds to describe the as yet non-existent astronomical or Keplerian telescope and the three lens terrestrial telescope. To top off his achievement he describes the telephoto lens more than 200 years before it came into existence.”
