Star tracking arm corrected by cams

thingiverse

Innovative Solution, Modern Twist A French astronomer, André Hamon, shed light on a mechanism to rectify errors in tangent drives back in 1953 through an article published in the bulletin of the Société Astronomique de France. His "How to" guide meticulously detailed how to draft the profile of cams onto a transparent plexiglas sheet using a ruler and a compass. - A complete scan of this article can be accessed here: http://www.astrosurf.com/astroptics/came_equat_hamon.html - An English translation of this article was published in Sky & Telescope in June 1978: https://archive.org/details/Sky_and_Telescope_1978-06-pdf/page/n73 Today, the digital equivalent of the drawing board is CAD software, and with a bit of adaptation, the same constructs can be accomplished on screen. Advanced tools also include CAM integration to drive digital manufacturing of designs. The objective of this project is to bring back an old technique to the attention of amateur astronomers or photographers who want to practice astrophotography using very long shutter times, ideally through the "Bulb" shutter mode of a digital camera.