ngc 6871

[alacant]

Hi everyone

Another what-to-image-at-full-moon senario. This was far enough away from said and a bonus to get gas and dust or whatever it is. Cygnus notwithstanding, we never expected anything other than dark background as has been the case with the other clusters in the area. Anyway, maybe worth more data... And then there's the processing. I did what we normally do for clusters. I think something else is necessary with dusty stuff however. Any recommendations?

Thanks for looking and clear skies.

700d on nt150s: 90 minutes @ ISO800

[sloz1664]

Love the detail in this image. Regards bringing out the dust clouds, that depends on which image processing software you use. Just a slight comment. You're blue stars have a greenish hue on my screen, but his could be the image down to the image conversion software.

Steve

[Guest]

clear skies and as usual, lovely image !! we have clouds here !

[alacant]

10 hours ago, sloz1664 said:

blue stars have a greenish hue

Yeah, I'm sure you're right. I'm hopeless with colour. I think part of the problem is the variation of colour you get on different devices. 'Phones and tablets tend to give exaggerated saturation to colours whilst laptop screens seem more conservative. My gf's ipad is the worst I've seen for falsifying photos; perfect for facebook of course.

Here's another go... Dunno... Taken the green and blue down but have lost the dust in the process. Can't win!

 

[Susaron]

You missed Sh2-101 the Tulip Nebula is just beside this clusters, with the 130PDS you can get both on the same frame. See below

[ollypenrice]

Quite a discovery! That's a really interesting patch of gas and dust.

One way to enhance it would be to lift just the glowing background in Curves. So you'd pin the curve in the dark dust and maybe put a fixing point below that if you have room. Then mouse over the image to find where the attractive glow is on the curve and lift that gently. Then pull the curve back down again just above that and restore the upper part of the curve to its original straight line.

However, when chasing anything in the background sky you really must avoid black clipping. A screen grab shows the severity of the clipping in this case.

Compare this with a similar cluster-in-Milky Way shot without the clipping:

Much of the data you're trying to pull out has been discarded by black clipping.

Olly

Edit: It's interesting to note how similar the histograms are in other respects.

 

[wimvb]

That's a very nice image, considering the full moon was about. Probably there was so much stray light, that 90 minutes on a dslr still had a lot of noise. Only more data can correct this.

The success with revealing background is totally dependent on how well you succeeded with calibration. Trying to correct flat fielding and sky glow, for instance, is a nightmare in dusty milky way images. But once you've got that under control, you can work on colour balance. Most often you need to reduce green in any image. Photoshop has HLVG (hasta la vista green), PixInsight has scnr.

Personaly, I avoid any pixel clipping during processing. Only at the very end, do I adjust the blackpoint to its final position.

[alacant]

2 hours ago, Susaron said:

with the 130PDS you can get both

Ahhgghh, yes. Too busy testing the ekos git to think about ap!

2 hours ago, ollypenrice said:

discarded by black clipping

Good point. I don't think I'm gonna be able to get the black point correct on this; full moon and the gradient it throws up needs an agressive blur layer to shift:(

1 hour ago, wimvb said:

PixInsight has scnr

StarTools: Gap Green

Anyway, patience rapidly running out, had one last go...

Thanks everyone for the useful input and your time.

 

[sloz1664]

That's pulled out the nice detail effectively. The Cap Green has worked quite well.

Steve