Ouroboros

Absolutely superb. The detail is fantastic. I take my hat off to your dedication and perseverance.

I’m a serial monogamist. I only use one of my three scopes at a time.

A 30cm dew strap from W&W Astro just arrived in the post for my new Askar FRA300. All tested and working. Unfortunately it came with clouds. I’m sure the forecast for tonight was clear. No longer it ain’t! Sorry.

I did have a brief OMG moment when I first glanced up.

I don't know if you can see this mobile phone pic, but this is what I could see just after I set up for an evening of astrophotography. Those light beams stretched right overhead. Some kind of light show in the town consisting of bright search-light like beams flashing and dancing across the sky. I don't know. Shakes head in despair. It's a reasonably clear night, the Moon is out of the way, and some nerks insist on flashing lights around. Fortunately I am using a dual band so I'm hoping it won't affect things. But anyone doing visual or broadband might be miffed to say the least.

Wow! That is a fantastic image. You really have pulled out the detail in the dust. Nice to see the bubble so well. Personally, and this isn’t a criticism because it’s all a matter of personal taste, I don’t like the colour pallet. But then, I instinctively react against false colour astrophotography unless it’s for justifiable scientific reasons. I know that’s against the current trend, but there you are. That’s my view. Given the obviously good quality of your data, have you considered processing it more realistically? Might be interesting. The crescent nebula looks like you’ve got lots of OIII there. Keeping Ha as red and OIII as green/blue might look very striking.

Fantastic image. I am so impressed with what some of you ‘real’ astrophotographers can do. Thanks for posting your workflow. So useful for those of us still padding around in the foothills of astro processing. What does integer resampling do for you?

Interesting. I was wondering whether doing some initial stretch to the whole image followed by star separation might have provided a better approach. I had to look up DDP as I have not come across it. It is available in Pixinsight, but seems to be considered obsolete compared with other methods. That’s not to say it is in the applications you’re using of course, and anyway seems to work for you.

Very nice colours and nice image generally. You must have been up half the night processing. It is a fascinating set of objects though isn’t it? Coincidentally I had another go at widefield imaging the whole Cygnus Loop last night. I packed in about 11pm after getting three hours of data. I want to get a few more hours of data before processing. I had my first go at dual band imaging this region a few days ago. How did you find separating processing the stars? I found stretching the stars to give a satisfactory star field difficult. Did you separate the stars at the linear or nonlinear stage?

Very nice pic. And great to capture that in such a short time. Oh, I know the Cornish weather very well. Warm, wet, westerly winds as they taught us in school geography. Not 'arf!. Some of the best astronomy weather I've had down there is when the weather has been coming from the east.

Surprisingly we had clear(ish) skies here yesterday evening. I was beginning to give up hope of ever testing my new Askar Colour Magic 6nm dual-band filter with my recently acquired Askar FRA300 I posted on in October. Inevitably perhaps the first target had to be the Cygnus Loop. I should really have framed it differently. I've chopped off some of the object at the bottom of the picture. But I didn't know whether I was going to get 20 minutes of clear sky or several hours. So I just went for it and in the end managed a modest 71 x 120s reasonable subs out of 85 or so. I found my first process of dual-band interesting, and need to study how to do this rather better. Stars in particular were a bit of a challenge. Using an unfiltered star field would probably be better I imagine.

What a fascinating object and an excellent image of it. It looks three dimensional.

It is too aggressive. It took me a long time to realise this fact. Unfortunately a lot of introductory videos use the STF/Histogram as the standard method to stretch to non-linear. So you sort of assume that's the correct way. They should really carry a health warning. For a while now I've been using GHS as my go to stretcher.

Yes, better still. I should have run NoiseXT slightly harder maybe.

OK. So this is my most recent effort after reviewing some of your comments. I think I’m still struggling but at least the blotchiness in my initial attempt has largely disappeared, and I’ve managed to pull up some of the background not unlike your various examples. I could go on fiddling with it for example by attenuating the noise a tad more. Incidentally I didn’t start applying noise reduction until towards the end. Anyway, thanks for all your help everyone.

Thanks, Bryan. I will look those out. I like AB’s vids.

@Nikolai De Silva Excellent. Amazing what they did with photographic plates isn’t it? I bet someone had to guide those long exposures by eye for the whole duration of the exposure too. Also amazing that those images were the best of what could be achieved then with big very expensive equipment ….. and that people can now produce better images in their own back gardens. The coloured plate of spectra is amazing. I checked my own copy of encyclopaedia Britannica published in 1953 and it does not have such good images.

I was interested and intrigued to see @bdlbug how you returned to generalised hyperbolic stretch again at steps 18/19. I don’t expect you to recall why you did that here but is that something you do regularly? I’ve come across GHS as a means to stretch in a more controlled way from linear to nonlinear than is achieved by using the STF + histogram transform method. But I haven’t seen it used in the later stages as you have here.

I see what you mean. I’ve only recently started using StarXTerminator. Perhaps a bit slap dash of me, but I have so far naively assumed, unless the residues left behind are really bad, that since I’m going to put the two images back together they’ll be hidden again*. Previously I used Starnet2 for a short while. I thought StarXT did a slightly better job on balance. I didn’t use filters with this image. It’s straight OSC. The haloes could be caused by faint mist I suppose. Perhaps I should reblink the original subs, weed out if necessary and reprocess. * I can see this doesn’t necessarily work because the starless image is probably going to get stretched more than the stars image.

Hey! Lots of responses. Thanks all. Yes, my experiments with TGVDN last night seems to confirm this. Yes. In fact I’ve played around with this image so much I’m having difficulty seeing it anymore. Thanks for the breakdown of your workflow. I very much like your second attempt particularly, along with @Fegato’s, for the way you’ve brought up the background nebulosity. Indeed it is. My recollection is that I got three hours of good data and then the mist rolled in off the Atlantic. Thanks for taking the trouble to provide your workflow. I shall study that. You’re right - there are any number of ways to skin a cat process an image. It’s one reason I take so long to process an image. Three steps forward, two steps back. Your comment about giving the data a bit of noise reduction at the linear stage. I think I have that stuck in my head as recommended procedure when I first started learning PI. Warren Keller even has a section on it. Kill the noise before you stretch it seemed to be the idea ….. but not to the extent that you kill the important details. Anyway, maybe that rule of thumb has been superseded. I also like the way you’ve developed the background. You’ve lost the purple colour and made it look more misty. Nice. You’ve also brought up the Cave Neb nicely too.

Yes. I often use a mask with it too to target the background for example. Those residual green casts can be quite subtle can't they? It's not until you remove them does it become obvious that they're there.

Thanks, @Fegato. Your background looks much better than in my effort, which encourages me to have another go.I think we all agree there is insufficient data. But then I’m thinking of this as a learning exercise. I am amazed how quickly you produced a result. I work very slowly, not least because I don’t quite know where I’m going so I spend ages on each process trying something, going back, trying something else. But how else can you come to understand what is after all a very complicated processing tool which can be applied any number of possible ways to achieve different results?Watching videos only takes one so far.

OK Let's see if this works ... This is 90 x 120s pre-processed data. All I've done is a slight dynamic crop of edge effects. Enjoy! NGC281_dc.xisf

well, just tried that by halving the resolution (ie reducing the image height and width by a factor of two, if that's what you meant) and it made no discernible difference. Thinking about it anyway, what you're looking at is reduced resolution because I reduced image size by a factor of about 5 before saving to jpg to post. .... and I don't think it is a particularly good image in that the framing could have been better ie the nebula could have been more central, but that's in the data acquisition stage.

Very nice pic. It’s interesting comparing the two. It took me a while to get my eye into spotting the similarities and differences. Interesting to see how the different techniques compare and what each bring out. I’m not sure my blotches appear in your image. But I’m going to reprocess mine and see what I get. Ta!