Inside the Camera Obscura: Kepler's Experiment and Theory of Optical Imagery

Abstract

In his Paralipomena (1604) Johannes Kepler reported an experimentum that he had seen in the Dresden Kunstkammer. In one of the rooms there, which had been turned in its entirety into a camera obscura, he had witnessed the images formed by a lens. I discuss the role of this experiment in the development and foundation of his new theory of optical imagery, which made a distinction between two concepts of image, pictura and imago. My focus is on how Kepler used his report of the experiment inside the camera obscura to criticize the account of image formation given in Giovanbattista Della Porta's Magia naturalis (1589). I argue that this experiment allowed Kepler to sort out the confusion between images 'in the air'-referring to the geometrical locus of images in the perspectivist tradition of optics-and the experimentally produced 'projected images', which were empirically familiar but conceptually alien to perspectivist optics.

El dualismo cartesiano y la glándula pineal: de la fisiología al arte

“…Así, la vista no sería otra cosa que una máquina de representación que funcionaría de forma análoga a una cámara oscura (figura 10), cuyo principio se conocía desde la Antigüedad, siendo un instrumento de uso habitual entre los artistas de su tiempo, que la llevaron a su máximo desarrollo. De he-cho, la nomenclatura del artilugio como "cámara oscura" es coetánea a Descartes, pues se debe a Johannes Kepler (1571-1930), quien denominó así al aparato en su libro Ad Vitellionem Paralipomena…, de 1604 (Dupre, 2008). Debe reseñarse, por lo demás, que el Discurso del Método de Descartes, aunque publicado en solitario y de suerte anónima en Leiden en 1637, se concibió originalmente como un prólogo a la Dióptrica, Meteoros y Geometría, textos que se publicarían luego bajo el título general de Ensayos Filosóficos.…”

Camera Obscura

“…It did so first in the work of Giambattista Della Porta, who also used the camera for its more theatrical purposes. Although Della Porta's optical conceptualizations did not stand the test of time, his comparison between the camera obscura and the human eye provided much inspiration to Johannes Kepler (Dupré 2008). A key element of this comparison was the identification of the retina with the screen in the camera obscura.…”

Kepler: Analogies in the search for the law of refraction

“…"You could now guess immediately", insists Kepler, "that because the hyperbola does the opposite of the refractions, the ellipse, being the hyperbolás opposite, is going to do the same as the refractions, and will accommodate itself to the measure" (Paralipomena, p. 112; GW II, p. 95). Kepler tests an algorithm that is similar to the previous one but that uses an ellipse rather 17 S. Dupré studied the Kepler's analysis of these types of experiments in S. Dupré, 2008 andS. Dupré, 2012.…”