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NGC 6188 - nebula


jsmoraes

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After many trying to catch and process this nebula, I believe that I can't do any better image with my set of equipment of photography: stock color Canon 1100D and UHC (Halfa + OIII) filter. Captures near Halfa cause much granulation on Red channel and low amount of data.

GSO 305 mm  -  Canon T3 - OAG - UHC filter - coma corector

20 x 5 min - ISO 800

9 x 5 min - ISO 1600

n6188-full-rgb.jpg

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That is a very nice image. Impressive for an unmodified camera. On my screen it seems that there is some green in the dark parts. That would be easy to remove with HLVG (in PhotoShop) or SCNR (in PixInsight).

Thanks for sharing

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Thanks for comments. It sounds very nice to me. This work was the most difficult I did. 3 days: 2 working only with the 9 best FWHM with ISO 1600, and  one with 9 ISO 1600 and 20 ISO 800 (because of the half Moon brightness).

I used the gray R, G, B channels as you do if they were done with mono camera. The color channels from Autosave.tif 32 bits were converted to 16 bits each one and were enhanced to have the best appearance and details, before rgb composition.

As I told the Red channel is terrible ! My Canon show much white granulations background when near Halfa spectrum. As there were many stars. Smooth them is a hard task.

My UHC Halfa + OIII type filter give me as much green data like it do to blue, also.

 
To balance and improve the global color information is a insane task.

Only to adjust color:

process-layers.jpg

And a similar to final adjustment, sharp, noise filter. I didn't saved the process to show the amount of adjustment layers.

I gave up at least 3 times. But as "the harder, more tasty is the victory" ... I returned to work on it.

Quote

 Like a curtain or storm coming down.

Physicus, belive it or not, today was the first day that I could see as you told ! I have visual perspective troubles. I was seeing the brightness portion of the image (bluish down area) as top layer and the red area as bottom layer.

I have this problem when working with Moon's crater. The bottom appears at top surface and the top as bottom surface. Image on to see the craters as pizza, cake or warts; instead of hole ! 
This disorder of perspective stays swapping constantly, but some times remain for hours. I must stop to work, and wait to normalize.

It was a surprise in see the correct perspective of NGC 6188 today. And more than to like the photo,  now I love it !

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there is some green in the dark parts

wimvb, thank you for advice. I work with netbook and notebook. I can't see this green. I have HLVG plugin. What method you suggest: medium or strong ? The histogram in Photoshop shows a very small change in green channel. I am unable to do a choice. 

note: because of my perspective trouble, perhaps I lost some quallity and details inside the darker area at middle center of the photo. To me, as false background area ... the area was background sky. I processed to reduce the red information on it ! bangbang.gif

I don't know if I will be able to recover those informations. I will try although !

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On my laptop screen, I can see very weak green in the dark patch in the upper part of the image. I don't use Photoshop, so I don't know how to apply HLVG. If you use it, use only very little. Maybe someone who uses PS, can advise you better.

Still, it's a wonderful image as it is.

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I used the medium method. And I upgraded the image of the first message of this thread with the recovered red information inside the darker area of nebula. They are faint, but I hope it has improved the photo. It is a link to photo inside my album in the site of my Observatory. Perhaps with some time it would be upgraded automacally; I don't know if the forum create a copy.

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I don't know if the forum create a copy.

Now, I know that it doesn't make copy. The server of my site is out of service, and the image posted isn't showed.

new edition: it was worse. A crash on server lost the photo. I edited the message and upload again, but now as attached. 

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