Sh 2 155 The cave

[alan potts]

A good while ago Olly, who is known by most on here, posted advice along the lines of I use to take 3 images a night now I use 3 night for one image, it's always stuck in my mind and now do this. Last year i took a shot of this same subject and was fairly pleased with my 90min-2 hrs effort, i didn't realise how bad it was until I added another 7 hours of data. So heres a 90% selection of a total of about 9.5hrs taken over a year or so, still can't see a cave though.

 

   

Advice always welcome. Thanks for looking,

Alan

[Ouroboros]

 I’m not sure I’ve got any advice, Alan. The cave nebula is a very faint object as I found a few weeks ago when I just had a go at it one night a few weeks ago.  It’s tricky to process.   As you say, it needs a lot of data. I certainly didn’t get enough. I’m not sure you have either. You’ve done a nice job of getting rid of noise in the background,  but then the nebulosity still looks grainy. And there’s the rub isn’t it? One can smooth the background but not the faint nebula without losing detail.

Your stars are nice and tight.  Did you use any star reduction? The image might benefit from a bit more.  Did you try separating stars from nebula and working on then separately? 

[alan potts]

1 hour ago, Ouroboros said:

 I’m not sure I’ve got any advice, Alan. The cave nebula is a very faint object as I found a few weeks ago when I just had a go at it one night a few weeks ago.  It’s tricky to process.   As you say, it needs a lot of data. I certainly didn’t get enough. I’m not sure you have either. You’ve done a nice job of getting rid of noise in the background,  but then the nebulosity still looks grainy. And there’s the rub isn’t it? One can smooth the background but not the faint nebula without losing detail.

Your stars are nice and tight.  Did you use any star reduction? The image might benefit from a bit more.  Did you try separating stars from nebula and working on then separately? 

I understand what you are saying but in truth I don't know how to do this separating stars and nebula. I processed this in less than 5 minutes as I always do, I do very little to anything really, stretches and then sometimes selective colours boost. I may well add to it as I have a few clear night still before the Moon annoys me again. Anything I do that look decent is normally by accident. I tend to use Camera Raw Filter mostly as well as Select and Mask.

Alan

[Ouroboros]

@alan potts 5 minutes! Goodness. I often spend 5 minutes at least at each stage in the process. I often try something, don’t like it, go back or delete it, start again. I tend not to complete the entire image process in one go.  I save the file at each completed stage too so I can return to any particular stage in the process. That’s useful if I learn a new technique or think of a different method. Leaving an image and returning later means I spot problems I hadn’t seen before. 

[MartinB]

Very nice Alan, the dust is showing well.  As for separating the stars, if you have PI, PS or Affinity Photo you can use Russ Croman's StarXterminator.  It costs a few bob but well worth it.  Alternatively Starnet2 is also brilliant.  They are easy tools to use.

[alan potts]

14 hours ago, MartinB said:

Very nice Alan, the dust is showing well.  As for separating the stars, if you have PI, PS or Affinity Photo you can use Russ Croman's StarXterminator.  It costs a few bob but well worth it.  Alternatively Starnet2 is also brilliant.  They are easy tools to use.

Martin easy to use for me is a must. I tend to do everything quick and to eye, I have an excellent eye of colour and general composition in photography in general, I know I am never going to compete with many on this site so don't try to. I am happy with my shots and that's the main thing to me. May look at one of the star removal systems though.

Alan