Astronomical filter

Telescope accessory used to improve details of viewed objects

An astronomical filter is a telescope accessory consisting of an optical filter used by amateur astronomers to improve the details and contrast of celestial objects, either for viewing or for astrophotography. Research astronomers, on the other hand, use various band-pass filters for photometry on telescopes, in order to obtain measurements which reveal objects' astrophysical properties, such as stellar classification and placement of a celestial body on its Wien curve. Most astronomical filters work by blocking a specific part of the color spectrum above and below a bandpass, significantly increasing the signal-to-noise ratio of the interesting wavelengths, and so making the object gain detail and contrast.

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