At the Telescope

  • Steve Massey
  • Steve Quirk
Part of the Patrick Moore’s Practical Astronomy Series book series (PATRICKMOORE)

Before we venture off into the practical side of a typical video imaging session under the stars, it is worth mentioning just a few of the commonly employed camera accessories and configurations you may find useful. Some configurations may require the use of threaded step rings or other adapters to allow for successful attachment.

4.1 Focal Reducers

Focal reducers are great for producing a wider field of view, especially when using cameras with small CCD image sensors. They essentially reduce your telescope's focal length so that it performs like an instrument with faster optics of the same aperture, yielding brighter images. Some can introduce coma (elongated stars appearing around the edges of the field of view) and may require a coma correcting lens also to ensure a flat field of stars across the entire image.

Another point of note is that certain telescopes with fast f/ratios like Newtonians and some short tube refractors may experience inward focusing problems when used with a...


Filter Selector Planetary Nebula Flat Field Focal Reducer Frame Accumulation 
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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • Steve Massey
    • 1
  • Steve Quirk
    • 2
  1. 1.Hervey BayQLDAustralia
  2. 2.MudgeeNSWAustralia

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