TerryMcK Posted March 26, 2021 Share Posted March 26, 2021 Processing this was fairly difficult due to lots of local light pollution. Also I think the main stars are a little too bright and maybe I could revisit it. I bought a new William Optics x0.8 reducer/flattener which got most of the cluster in frame with my WO ZS73. My normal flattener is non reducing and gives a field of view slightly too small for larger objects like M45. Also as a bonus the reducer/flattener has a graduated camera rotator so you can set it easily. The original one, although it does have a camera rotator, is not graduated so not as easy to use. After a lot of messing about with PixInsight I just could not get rid of the local light pollution which appeared in the top right of the frame. In reality this was the area nearest the ground. A neighbours house is lit up like a Christmas tree until 10:00PM every night and I got some spillage from his lights despite the IDAS D2 LED blocking filter. So rather than doing pre-processing in PI I decided to do it in AstroPixelProcessor. This stacked all the subs as normal but has a routine you can call up called "Remove Light Pollution". I have not used it before but it is on the Tools menu. Essentially you have to specify a minimum of 5 sampling boxes which you draw onto the finished stack. I specified about 12 in the areas where the pollution was strongest. Then you click calculate and it gives you opportunity of previewing the results. If you don't like it you can tweak the position of the sample boxes. I clicked calculate and bingo the pollution was gone and it left the nice bits untouched. I then loaded the image into PixInsight and carried on with the processes I like. The following is the results: Telescope: William Optics ZS73 with x0.8 reducer - focal length 344mm f/4.7 Camera: ZWO ASI183MM Pro one shot colour camera Filter: IDAS D2 Exposures: 2.5 hours comprising 119 x 30 second @ Gain 111 Offset 8, 48 x 120 second @ Gain 111 Offset 8 Terry 1 - Insecurity lights 0 7 Quote Link to comment Share on other sites More sharing options...
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