Hello, sorry late answer. Thank you for looking into this!
Please check the image.
On left images preprocessed, streched by histogram, applied background extraction, converted to tiff and roughly stiched.
BE does not work good here, as top of one image does not match bottom of image above.
On right, preprocessed with flats rotated 180 degrees(!) and streched by histogram. If I didn’t rotate my flats the result would be about the same as on left side but without the very dark areas in sky near horizon on left. Those areas are impossible to deal with when stiching.
When I add more columns the stich between columns is not very visible.
On right side you see that the bottompart is OK, but the top part of picture is not so good. I think it’s because its not correct way to solve this by rotating flats. I need to keep the flats the way they are, but I need to apply gradient from top to bottom in each image to remove the artificial gradient.
Please note that I need to keep the natural gradient. SInce camera is on a wedge the gradient near horizon goes from lower left corner in image, to upper right corner.
I think the gradient may be from heat distribution in camera spreading to sensor, either internal motherboard or from heater strips I had to use in the panoramic head to make it work at -20 celcius.
Do you have any tricks on how to apply gradient to my flats?