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H-Alpha N America NGC 7000 (WO51mm EOS Ra).jpg
A portrait in monochrome of the rich nebulous region around the North America and Pelican Nebulas in northern Cygnus, with the star Deneb at right of centre. This is shot through a deep-red narrow-band filter that lets through only Hydrogen-alpha light, the emission line that nebulas like these primarily radiate at. This was taken in a bright moonlit, though rural sky (with a waxing gibbous Moon in the opposite side of the sky) as a test of a new autoguider system and through the William Optics RedCat 51mm f/4.9 astrographic refractor, also under test. The camera was the Canon EOS Ra, sensitive to H-a light. The filter was the 12nm Astronomik clip-in filter. The field is about 8° x 5°. This is a stack of just 6 x 12-minute exposures at ISO 2500. Due to the low signal through the dense filter and the fact that only 1/4 of the Bayer-array pixels are receiving signal, such images really need lots more exposure time and sub-frames to do the best job and keep noise down. Local contrast adjustments made with luminosity masks created by Lumenzia extension panel.