The Celestron #93598 Piggyback Bracket fits their 8-14" diameter Schmidt-Cassegrain telescopes, and is a popular and easy way to get started in astrophotography.
Stunning, remarkably detailed wide field photos can be taken by attaching your SLR camera atop the telescope in the equatorial mode, guiding the camera through motion of the telescope itself. It certainly helps to have a fast aperture lens for the camera, such as the f/1.2 50mm, 55mm and 85mm lenses available to fit various manufacturer's systems, as this helps drastically shorten the exposure times.
The slotted mounting holes in the base of the piggyback bracket allow it to be installed in predrilled threaded holes on the rear cells of any of these scopes. The piggyback's broad base is designed to only fit the curvature of the specified Celestron telescopes, and won't work properly upon other models.
