Essays about Hans Lipperhey (1570-1619), Christiaan Huygens (1629-1695), Dirk Klinkenberg (1709-1799), Frederik Kaiser (1808-1872), Jacobus Cornelius Kapteyn (1851-1922), Joan Voûte (1879-1963), Jan Hendrik Oort (1900-1990) and Ewine van Dishoeck en Imke de Pater and their contributions to the history of the telescope, written to accompany an exhibition at the Museum Boerhaave held from 10 september 2008 until 19 April 2009.