Author Topic: Crescent Nebula..Need help  (Read 2079 times)

Offline sreilly

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Crescent Nebula..Need help
« on: 2014 August 30 13:55:06 »
I've been spending the past two weeks gathering data on this object. I started with Ha and then some RGB. Discovered I was having issues with the filter wheel and started over again. Long story short is I have processed an image using the best of the data that left me with a 13-1/2 hour RGB image, 5 hour Ha image and 5-1/2 hours of luminance. The full range of images sizes can be seen at http://www.astral-imaging.com/NGC6888-RC2.html and http://www.astral-imaging.com/NGC6888_LRGB-RC2.html. I added the Ha data using the NBRGBCombination Script but it did not get posted yet. What I was disappointed in was trying to bring out the faint bluish hue that is present in the central area and leading top right area of the nebula. Of course I want to keep the image from having a "processed" look if possible. The Ha won't help in this respect and I haven't been able to get a clear night to shoot OIII which should help.

Any suggestions on bringing out this faint detail would be greatly appreciated. Of course I also realize that maybe that isn't going to be possible without the additional OIII.

Thanks for any suggestions.

Steve
www.astral-imaging.com
AP1200
OGS 12.5" RC
Tak FSQ-106ED
ST10XME/CFW8/AO8
STL-11000M/FW8/AO-L
Pyxis 3" Rotator
Baader LRGBHa Filters
PixInsight/MaxIm/ACP/Registar/Mira AP/PS CS5

Offline sreilly

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Re: Crescent Nebula..Need help
« Reply #1 on: 2014 August 30 15:14:03 »
Replying to my own thread, I was reading an article I had copied from Sky & Telescope June 2011 by a great amateur imager named R Jay Gabany. I had seen him several times over the years at the AIC conferences in California several times. His primary choice of software, at least at the time, was Photoshop and he developed a process he called Layered Contrast Stretching which I just tried on this image. It seems to have been able to bring out the faint detail that I'm trying to reveal. So with that said, and I don't know if it can be replicated in PI without layers although I suspect someone with a good working knowledge of Pixel Math could most likely accomplish this. To bring out the faint detail, a copy of the image was made as a second layer. The layer then had a Hide All mask added and the blending mode was set to screen. Using the brush tool and a very low flow and opacity rate (15%) you brushed over the area of interest using multiple strokes to build up the effect. In my case this was all that was needed but he also had a second layer added with the blend mode set to soft light which increases contrast and color using another mask to add to areas needing it's assistance.

So the question begs to be asked, is there a way to do this in Pix Insight at this time? Image posted at http://www.astral-imaging.com/NGC6888__LRGB_RC_1600LCS.htm with a darker version here http://www.astral-imaging.com/NGC6888__LRGB_RC_1600LCSd.htm

I hope I don't ruffle any feathers with this post but I would like to learn a way to do this in Pix Insight.

Many Thanks,
Steve
www.astral-imaging.com
AP1200
OGS 12.5" RC
Tak FSQ-106ED
ST10XME/CFW8/AO8
STL-11000M/FW8/AO-L
Pyxis 3" Rotator
Baader LRGBHa Filters
PixInsight/MaxIm/ACP/Registar/Mira AP/PS CS5

Offline ajbarr

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Re: Crescent Nebula..Need help
« Reply #2 on: 2014 August 30 19:09:45 »
Steve if you want to get more detail and the blue envelope, I think you need OIII. I did a bi color of the Crescent not too long ago. with just 1.5 hours of Ha and 1.5 of OIII. Here's my result.

Albert