Popular Post Clive Posted March 24, 2020 Popular Post Share Posted March 24, 2020 Having captured 120 images of M101 on Sunday night, I pulled them into DSS and left it to do a 100% kappa sigma stack whilst I got some sleep. On Monday morning I pulled the resulting image into IRIS and was somewhat horrified at the noise level, not much better that a single image! So I spend all day Monday trying to trace the problem. I have always found that a kappa sigma stack is noisier than a straight average stack of the same images and performing an average stack on the 120 subs resulted in a final image with negligible noise as expected (but with all the accompanying satellite / plane trails and hot pixels). To cut a long story short, I found that the noise in the final image of a kappa sigma stack fell as the number of subs increased (as expected) but only up to about 60 subs – adding more caused the final image noise to start increasing again. In the end I kappa sigma stacked the images 30 at a time and then averaged the resulting 4 images in IRIS. That gave me a resulting image with a noise level just slightly higher than that achievable using average stacking but without the trails. These are the resulting images; the first is just slightly smaller than full frame, the other obviously a cropped enlargement of M101. Usual setup of my Canon 200D with 400mm at F5.6 and ISO1600. These are from the stack of all 120 x 180s subs (6 hours total) but just 30 subs gives a result not so dissimilar. +seven_legs, +Graham, Bottletopburly and 6 others 9 Link to comment Share on other sites More sharing options...
+Graham Posted March 24, 2020 Share Posted March 24, 2020 Loving the cropped version. Clive 1 Link to comment Share on other sites More sharing options...
Bottletopburly Posted March 25, 2020 Share Posted March 25, 2020 Nice work Clive have you tried stacking in siril , Clive 1 Link to comment Share on other sites More sharing options...
Clive Posted March 25, 2020 Author Share Posted March 25, 2020 5 hours ago, Bottletopburly said: Nice work Clive have you tried stacking in siril , No I haven't, I'll have to download it and give it a try. Do you consider it better than DSS? Bottletopburly 1 Link to comment Share on other sites More sharing options...
Bottletopburly Posted March 25, 2020 Share Posted March 25, 2020 35 minutes ago, Clive said: No I haven't, I'll have to download it and give it a try. Do you consider it better than DSS? Siril is iris Clive it can be a bit daunting a lot of info is in french but I found using the scripts very easy , simply a few clicks of the mouse you can view the actions of the scripts by clicking on each script , I use the no darks script https://gitlab.com/free-astro/siril/raw/master/3rdparty/scripts/en/DSLR_Preprocessing_NoDark.ssf so all I need is a folder containing three folders lights flats biases as I dither , no need to go through all the options like DSS , so load files in relevant folder tell Siril where these folders are, (called the working directory) and choose the script you want ,so if you are a bit more pc savvy than me you can create a script to your own specific needs , and to add data to previous sessions you can align the stacked results together from each session can’t remember off top of my head how to do it But was pretty straightforward tutorials on YouTube https://www.youtube.com/channel/UC_8UVzay-xlds4pjyRhHUOw Link to comment Share on other sites More sharing options...
Clive Posted March 25, 2020 Author Share Posted March 25, 2020 Ooh, I like scripts! I use Excel to generate them for IRIS to do all my processing 😁 Bottletopburly 1 Link to comment Share on other sites More sharing options...
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