Author Topic: Strange DBE Effect  (Read 638 times)

Offline borwin

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Strange DBE Effect
« on: 2017 November 30 04:14:37 »
Has anyone come across this result after a DBE? 

I'm getting it on a few images now.  I have been successful with the DBE process before, but am still trying to determine the best settings....and can''t get back to what worked earlier.  I attached a before and after DBE as well as my DBE settings from PI.  Just a note on the settings screenshot, this was before I moved each 'x' onto black background.  I did spend a lot of time moving each one to assure a good bkrnd calculation.

The before is a dark subtracted flat calibrated, registered and stacked light.  And using this same data I had a much better DBE result in he past.

Thanks

Offline pfile

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Re: Strange DBE Effect
« Reply #1 on: 2017 November 30 11:27:11 »
i think you have way oversampled this image - i'd start with like 10 samples around the edges and into the areas where there is no galaxy and see what you get.

rob

Offline borwin

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Re: Strange DBE Effect
« Reply #2 on: 2017 November 30 12:14:36 »
Thanks for the reply
10 samples per row or 10 total?

Offline pfile

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Re: Strange DBE Effect
« Reply #3 on: 2017 November 30 13:42:04 »
10 total.. but that's jsut a ballpark. for galaxies what i usually do is hit the corners of the frame (corners where there is no galaxy), then a few points in the 'triangles' where the galaxy isn't, and then along the outer edges of the frame at the middle points.

also make sure to avoid any and all stars, especially the halo around bright stars. if the background does not look proper, then start adding points sparingly where the model was not correct.

i'd only do a grid like this if i had a seriously complex gradient with lots of bright/dark spots. if you have that, and you need to do a grid, you need to keep the points well away from the faint areas of the galaxy and again make sure you're not on or near bright stars.

rob