Astronomy Specialist



Telescope Aperture
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Schmidt-Cassegrain telescopes have the advantage to have the closed tube by the correcting plate. This plate protects the mirrors from dust and dirt but once in a while it is recommended to clean the optics so the telescope can perform at its best.

The external side of the correcting plate is the only optical surface to be exposed to atmospheric agents and it gets dirty quite easily but it does not require a telescope disassembly. This plate is fully multi-coated with anti-reflective coating layers so it cannot be cleaned as a standard glass, and it can get scratched quite easily. Also the wrong cleaning agent can leave halos or worse, it may permanently damage the coatings.

Extra caution must be used to get access to the internal side of the correcting plate. When the correcting plate has to be removed from the tube, it is very important to keep track of its position on the tube: it should never been rotated. In fact, the correcting plate is positioned to minimize the overall telescope astigmatism

Generally the primary and the secondary mirrors do not need to be cleaned as they are protected by the correcting plate. When necessary, mirrors need to be cleaned very carefully. The reflective aluminium layer is extremely thin and can easily get scratched. Never clean a mirror with a dry cloth or tissue! The dust particles captured by a dry cloth will be carried across the mirror leaving permanent scratches.

At the end of the cleaning process, the optics need to be realigned and the correcting plate must be centered with the Hotech laser collimator. 

Testar offers the service of Schmidt Cassegrain cleaning & collimation that consists of:

  • cleaning of the internal and external surface of the correcting plate
  • cleaning of the primary and secondary mirror (when necessary)
  • dust and dirt removal inside the tube
  • general cleaning of the optical tube
    A collimation & cleaning certificate will be provided with the telescope. 


    Schmidt Cassegrain Cleaning


    8" Aperture

    $ 369.00

    9.25" Aperture

    $ 399.00

    11" Aperture

    $ 499.00

    12" Aperture

    $ 549.00

    14" Aperture

    $ 799.00

    16" Aperture

    $ 899.00

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