GSO 305 mm - Canon Rebel XT - iso 1600 - 13 m - 26 frames
medium scale
http://i1063.photobucket.com/albums/.../ps_m17_1k.jpg
large scale
http://i1063.photobucket.com/albums/.../ps_m17_2k.jpg
In this photo was used some tips from Alpal to better working with stars. Despite I haven't full knowledge of mask use, I feel to be in a good direction