Full resolution (1497 x 1007 pixels) cropped image of the central portion of M-17
taken with an AP 140 F7.5 Starfire EDF Astrograph Refractor with 4" focuser.
The instrument was working at F5.7 with the 155TCC Telecompressor Corrector.
STL11000 camera with Baader 50.8 mm Unmounted Narrow Band CCD Imaging Filters for STL Cameras.
Exposure: 2 x 20 minutes H-alpha and 2 x 20 minute O3. Red = H-a, green = 1/2(Ha + O3), blue = O3.
This cropped image retains the full resolution of the STL11000.
Note the incredible detail throughout the image!
Image by Roland Christen.