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Need advice with removing LP and gradient

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Hi all, I need some expert advice. I took 14 x 1 min exposures of the M42. Unfortunately the position of it means it is prone to light pollution and also Friday night the seeing weren't the best, as my M45 picked up some reflected light pollution due to the wet up there. Normally I can process the images and get rid of the LP, but when I try to use the middle dropper in the levels in PS, I get left with a red mess of gradients.

If I use GradientXterminator, the LP gets removed but then I am left with weird gradients. It is a shame as in processing, I have even managed to capture detail in the Running Man Nebula, but can't remove the gradients to make it usable. If anyone has any tips to help then I would be most grateful.


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The last time I saw such a feature as you have at the bottom, it turned out to be a power line in the field of view. IMO, it is too abrupt to be a light pollution gradient. Anyway, this is extremely difficult to process out. Even if you manage to get rid of (most of) it, it is too close to the nebula, and will probably never result in a good image.

My advice is: examine the sub frames. If it is in only some frames, then remove these. If in all frames, then try to reshoot.


Good luck

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Thanks for the advice. Now you mentioned that, I think I know what that may actually be. As it was a bit windy the washing line was moving back and forth so I wonder if that is what blew in front of the scope. 

I shall check my subs and see if it appears in any other. If so then you mention that I will know what to look for in the future.

Thanks again.

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