Author Topic: Help me understand what I'm doing wrong with DBE  (Read 7964 times)

Offline cdavid

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Re: Help me understand what I'm doing wrong with DBE
« Reply #15 on: 2015 February 28 19:55:57 »
Wow!  That is a huge number of samples in DBE.  I was always under the impression given the other tutorials and reading on the forums that it was recommended to only use 6-8 per row.  Your result with my image is quite good. I will need start using more samples as you depict in the video.

Carlos


Offline jkmorse

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Re: Help me understand what I'm doing wrong with DBE
« Reply #16 on: 2015 March 04 17:24:37 »
Alejandro,

Like Carlos, I had always thought less is more until I saw your post and watched the video.  I am in the process of redoing an image of M74 that I always found disappointing and the change using your method with DBE is amazing!  By covering the background thoroughly, but avoiding any coverage of the faint arms of the galaxy (as well as all the little ones in the background) and the stars, brought out details I never saw before and really brings out those faint arms.

Thanks so much for the post, you made me a very happy guy  ;D  I can't wait to redo a number of other images.  I also am really looking forward to you and the rest of the Resources team adding more quality videos to your site.

Best,

Jim
Really, are clear skies, low wind and no moon that much to ask for? 

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Offline pfile

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Re: Help me understand what I'm doing wrong with DBE
« Reply #17 on: 2015 March 04 17:35:04 »
i think the advice to use few samples in DBE is good advice when you have images acquired from a reasonably dark site, because whatever gradients you have will probably be very well behaved and mostly linear in nature.

but when you start shooting from LP skies, or with moonlight putting funny gradients in your subs, the resultant gradient in your stacked image can become quite complex. for instance if i shoot into the light dome on my southern horizon all night, the integrated result has kind of a "u" shaped gradient. in that case you definitely need enough samples to pick up the complexity of the gradient.

rob

Offline jkmorse

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Re: Help me understand what I'm doing wrong with DBE
« Reply #18 on: 2015 March 04 17:43:03 »
Rob,

Great point.  My skies are nice and dark above 30+ degrees but there are light domes on the horizon, especially to the east (damned Houston).  And, given that I am stacking images taken all night, they are picking up artifacts from all over the sky.  In any event, for me and my location, the "many points" solution is the way to go.

Best,

Jim 
Really, are clear skies, low wind and no moon that much to ask for? 

New Mexico Skies Observatory
FLI Microline 16803
Planewave CDK17 - Paramount MEII
Planewave IFR90 - Astrodon LRGB & NB filters
SkyX - MaximDL - ACP

http://www.jimmorse-astronomy.com
http://www.astrobin.com/users/JimMors