problems after background extractor

[labtech1122]

hi, please can someone help.

when i go into pixinsight and go to either dynamic or automatic background extraction it always comes up like this in the end.

attached is the image before, the background removed and the image after

 

i have also included what happens to my image when i stack it with the flat, it seems to well over correct and remove alot of the galaxy too

[Elp]

Did you use a filter? What calibration frames did you apply? Sometimes this sort of thing happens if your flats haven't been calibrated properly hence the over correction.

Adam Block's got some good videos discussing this on YT.

Edited March 6, 2023 by Elp

[labtech1122]

16 hours ago, Elp said:

Did you use a filter? What calibration frames did you apply? Sometimes this sort of thing happens if your flats haven't been calibrated properly hence the over correction.

Adam Block's got some good videos discussing this on YT.

Hi, no filters have been used. The first image is with no calibration frames and after a dynamic background im PI the final is with dark and flats. It end up like the final image if I put any calibration frames in, I have tried doing one tried them all (bias, darks, flat light and flat dark) I have tried doing all together. I've deleted the registration files and started again and it still does it.

I have been able to get an ok image without the calibration frames but I can't avoid the rings I get in the image (like picture 1) even if I don't do background extraction and just edit the image I still get rings. This is an image I got near to ok (although by the end of the process I lost all colour) but you can see there are still rings around the image

[labtech1122]

Also this is using DDS

Edited March 7, 2023 by labtech1122

[Elp]

With your calibration frames, do you make a master dark flat then subtract that from each of your flats before making the master flat?

The issue usually stems from your flats if not calibrated contain your bias signal so over compensate. You also don't need to use bias files if you're using dark flats. Try the above.

Background extraction also works better if you apply it to each calibrated image as a batch process before they're stacked (ie you have to apply calibration frames to each light frame, then batch process a background extraction to each image, then stack those images).

Edited March 7, 2023 by Elp