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Hello,
Here is an image of Nunki using the Bahtinov Mask on the Mewlon 180 with the DBK21AF04.AS colour CCD. I had a TeleVue x3 Barlow plugged in. The attached file shows the separate R, G and B Channels as well as the original RGB image.
It looks like the mask is acting as a diffraction grating that splits the white light into its Blue, Green and Red components, presumably generating mono chromatic diffraction rings located at the points indicated by the respective coloured arcs.
Remember, whilst this particular mask was designed with the formula of Focal Length (=2160mm)/180, resulting in a Bar Width=6mm and Bar Gap=6mm, the image was captured at x3 the focal length, 6480mm.
Cheers
Dennis
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