Equatorial Drive Platforms

  • Norman Butler
Part of the The Patrick Moore Practical Astronomy Series book series (PATRICKMOORE)


So what is an equatorial drive platform? Some prefer to call it a Poncet drive system, while others just call it an equatorial drive platform for Dobsonian tele-scopes. We’ll start with the most common name first. The Poncet platform was invented by Adrien Poncet in the 1970s. Poncet’s original platform design was a type of equatorial platform that was simple in design and function that uses a single pivot as one support and inclined along a plane that is aligned with the Earth’s equator along which two other supports slides. It was publicized in the January 1977 issue of Sky & Telescope magazine. The type of equatorial platform that Poncet constructed was made out of simple plywood, with a pivot made from a nail. Poncet also used Formica to cover the top of his incline plane along with the use of plastic 35-mm film canisters as bearing feet for the platform, on top of which he mounted a Newtonian telescope of a 6-in. aperture. Simply built, the Poncet equatorial platform and mount in its basic design and fabrication requires just the use of regular hand tools and common construction materials and hardware to build. The only real accurate and precise setting required is the angle at which the inclined plane of the Poncet platform is set at in order to match the angle of the Celestial equator (e.g., 39°). The Poncet equatorial platform with its simple design has been used to track in the equatorial mode, a multitude of instrumentation, including just about everything from small cameras, optical instruments, telescopes to an entire observatory. Its simple design and low profile has made it a very useful “retrofit” for Altazimuth mounted telescopes, such as the popular Dobsonian telescope. Those who use a Poncet equatorial platform simply place their telescope on top of its mount in a secure fashion to get the added feature of tracking in the direction of right ascension that’s accurate enough for visual observing at higher magnifications or even astroimaging.

Further Reading

  1. Davis, M. A large equatorial platform for a big Dob.
  2. Heijkoop, A. Heijkoop’s equatorial platform.
  3. Luton, C. Equatorial cradle.
  4. McCreary, D. The McCreary Mount.
  5. Philpot, W. Building an equatorial platform for my telescope.

Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  • Norman Butler
    • 1
  1. 1.TamuningGuam

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