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Single long exposure and comet processing woes...


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Well that is probably a bit strong!


I have loads of data but have to say it's  a challenge processing comet data...


This is just for a start... it's actually from a single 3 1/2 minute sub and shows the tail a bit so thought I'd get one up!



Comet Lovejoy C/2014 by sja88, on Flickr


Stacking other images in DSS is interesting. I'll be back with questions later!!



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Thanks all. Certainly is strange tail.


Use comet mode, it's easy :thumbsup:


Good image, if they are all like that you should be okay :)


Have a lot of similar data but mostly shorter subs. The above image was a longer one to see what was visible and has been edited/stretched in CS2 to get it as shown.


I have

39 1minute subs @ 800ISO

12 1.5minute subs @800ISO

and  18x 30s subs at 1250ISO

All with a load of correlating darks at the same length and ISO


I have not discarded any/many due to wind remarkably! But some are a little brighter/spoilt due to passing cars!


As for comet mode I have been using it. Bit strange though... my RAW (NEF files for Nikon) seem very dark when imported.


Mostly I have only stacked single groups based on sub length to see what comes out. I may leave the lot to stack together over night and see what happens!


I have tried various stacking options in DSS after registering the stars and then comet (mostly have done this manually but there is a way to automate most of it)


I have tried:


Stars and Comet stacking: Superb feature and this works but has some minor artifacts from removed star trails (not an issue). The main difficulty/issue as that when it does the second stack and subtracts the trailing comet and the star trails it also removes a lot of lighter data? The resulting TIF is very dark and I am struggling to stretch it to get any decent image out of the data.  


Comet Stacking: I think I have done this two ways and the results are better (more tail). I did one with Kappa Sigma Clipping and one with the Average (the default) stacking mode for lights. The former produced what appears to be the cleanest image and has no stars at all... and the latter had star trails.


I suspect there are better way's, either setting in DSS or using different software to get more out of this but I am a little stumped so any advice appreciated.


Here is the Kappa Sigma Clipping version


16071495107_16ce0175b5_b.jpgComet Lovejoy - no stars 10/01/2015 by sja88, on Flickr





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