Optical telescope
The telescope is more a discovery of optical craftsmen than an invention of a scientist. The lens and the properties of refracting and reflecting light had been known since antiquity and theory on how they worked were developed by ancient Greek philosophers, preserved and expanded on in the medieval Islamic world, and had reached a significantly advanced state by the time of the telescope's invention in early modern Europe. But the most significant step cited in the invention of the telescope was the development of lens manufacture for spectacles, first in Venice and Florence in the thirteenth century, and later in the spectacle making centers in both the Netherlands and Germany. It is in the Netherlands in 1608 where the first recorded optical telescopes (refracting telescopes) appeared. The invention is credited to the spectacle makers Hans Lippershey and Zacharias Janssen in Middelburg, and the instrument-maker and optician Jacob Metius of Alkmaar.
Observatory Naef Épendes
The invention of the telescope in 1608 and the subsequent improvements in optics led to the revolutionary progress of the 17th and 18th centuries. We call this type of telescope a refractor because it deviates the light coming from an object in such a way that its image is reversed ; observation is done through an eyepiece at the end of the tube, which allows magnification of the image. Bequeathed by Mr. Robert A. Naef, the observatory's precious telescope is a Reinfelder & Hertel with a diameter of 162.5 mm and a focal distance of 1435 mm - this allows a magnification of X150.