Ouroboros

Yes, thanks for this suggestion. I’m going to revisit the data later when I’ve got some time to experiment with different amounts of noise reduction at different stages. Just got to experiment.

OK. I can see the amount of noise with STF.

Yes. I use SCNR a lot. Usually later and very successfully to remove residual green after background modelisation and colour calibration. The green I’m referring to above is the bright green colour cast observed in many OSC images immediately after preprocessing and before you do anything else. I have read it arises as a consequence of OSC sensors having twice as many green sensors as red or blue. Just out of interest I just applied SCNR to a just processed green image. It goes sepia, and looks yuck! I think it’s better to apply SCNR when you can see what it’s doing in a controlled way, possibly masked too to protect certain areas.

Thanks for your thoughts on this. I’ll revisit the data and have another go by trying those things. I feel astro image processing is a constant learning experience. In a sense an image is never ‘done’. I’ve picked up a lot in the last year or so, and feel it’s good practise to go back and redo old data. The weather is lousy anyway so few opportunities to get new data.

You might be right when they first launched it. In fact the process included a box to check for linear. That’s gone now. I apply it early because not only does it work extremely nicely in linear but also because I thought it was recommended to do some noise reduction before stretching.

You’re right, but I usually found DBE applied early went a long way to dealing with the green cast too. I normally only do background neutralisation within SPCC. Seems to work anyway.

~F/6.5 with flattener/reducer. But yes, @Fegato, not oodles of data I agree. I did do DBE. I just missed it off my list. Traditionally I’ve always done DBE immediately after dynamic crop. But I read recently that it didn’t matter when you did it during the linear stage. This time I did it on the starless image after doing dynamic crop, SPCC, BlurXterminator and NoiseXTerminator on the original starry image, if you see what I mean. I’m not sure DBE would make much difference because the mottled features are on a smaller scale than the DBE background which is usually slowly varying. While we’re on the subject of applying DBE to the starless image ….. I too have followed Adam Block’s method on this. Have you noticed how applying DBE to a uncolour calibrated starless image does not get rid of the green colour cast you often see at the beginning of processing? Yes, I applied NoiseXTerminator on the unstretched linear image. I thought that was recommended.

I have recently had another go at processing 3 hours of OSC data of the Cave Nebula acquired last year with my SW ED80 and ZWO ASI2600MC. I’m reasonably pleased with the resulting colours and the look of the image overall. But I’m less happy with the blotchy colour in the fainter areas of nebulosity. Maybe it’s real of course or maybe three hours just isn’t enough. My workflow has been roughly as follows: Dynamic crop. SPCC. BlurXterminator. NoiseXterminator. StarXterminator to separate nebula from stars. Generalised hyperbolic stretch of starless and star images. Several selective applications of TGV Denoise applied using masks (to protect brighter areas). Curves applied to the starless image for contrast and emphasis of brighter regions. Colour saturation applied to brighter areas and to suppress some unsightly purple areas in the background. Some Local Histogram Equalisation to brighter areas and some Dark Structure Enhance. Recombination with stars. Desaturating colour in the background just looked artificial and unrealistic. So I ditched that approach. Any suggestions of possible solutions?

Ah .... got it now! Ta

@Craney I've been using the new Sat24. It's better than I initially thought. Have you found a way of moving the map? It seems to be stuck with the UK in the centre. Sometimes it's good to see further out to what's coming further out.

It is very interesting. At one time I was 100% in favour of recommending the ASIair, but my experience of late since recent software updates is that it has become flakier as a platform. All this has been debated at length elsewhere. I don’t know why this has happened. Whether ZWO have overstretched themselves in adding too many knobs and whistles to the air. I’ve no idea. Anyway, it’s worth knowing about alternatives in case jumping ship becomes necessary.

That’s an interesting thought. I had assumed it was solely a commercial decision to tie people in to the ZWO stable of cameras. In fact I thought they were being quite clever in enabling a lot of different types of DSLR cameras to work with the ASIair because they know that a lot of people transition from a DSLR to a dedicated camera.

I agree with @Bluesboystig’s comments. I’ve never tried the All Sky alignment but I am aware it exists. As for distance …. 25m is out of the question in my experience. Even ten metres from inside the house is pushing it. It’s not so much that it won’t make contact with a tablet or phone, but you’ll see slower downloads and more drop outs. I own two ASIair Plus and neither achieve the working distance claimed by the manufacturers. As it happens that’s not too much problem for me. In your circumstances I’d look at extending your home WiFi and control the ASI on your network. You’ll be able to be anywhere in your house then. I don’t know what other equipment you have, but an ASIair limits you to equipment (ie cameras) from the ZWO range, apart that is from some DSLRs and other mounts.

It's ironic isn't it? Just as we might have believed that some progress was being made controlling ground based light pollution - what with dark sky areas etc - they think of ways of light polluting the skies from above.

The plan is for tens of thousands isn't it? I see the amazon chappie (not to be outdone) is getting ready to start launching his lot. Look up in 20 years time and the night sky with be a fine white mist of satellites I reckon.

Personally I’d say that’s OK. That’s basically 50m cable reel extension length isn’t it? You can easily run a shredder or hedge trimmer down the garden you can certainly run an Astro rig. My astronomy shed is powered on the end of a 13A 50m extension cable. I run an astronomy rig, small light, small ancillaries like power supplies for a laptop etc plus, on occasion, a fan heater. It copes fine with that. My set up incorporates a residual current trip too just in case.

@DSOBug. That looks a very nice set up. Looks like your guiding is working and the stars are round out to the edges. Are you planning to stick with the DSLR for the time being or have you got your sights on a dedicated astro camera? Anyway, you should have some fun capturing some wide-field shots.

It’s ZWO’s new telepathic mode. You have to believe in it otherwise it doesn’t work.

I’ve just been looking at your image again, @R26 oldtimer, and have realised just how small a part of the Soul nebula it shows. It’s amazingly sharp. Good for a scope costing less than 300 quid isn’t it.

That really is good. Dark and menacing. 21hours. Phew!

If different applications produce more or less the same result then surely the two remaining considerations are ease of use and how long it takes. The former of those two is a matter of personal preference. As for the latter, does DSS do local normalisation? That seems to be the most lengthy process in WBPP. Also drizzle - not that I use that.

Very interesting question, @Bluemoonjim. It’s also one I can’t answer because frankly life has been too short to do a comparative test. But you have I assume, and you find no difference? Interesting. Mind you, I suppose there’s no reason in principle why there should be. I used to use DSS and then processed in Photoshop. I then got into Pixinsight and it seemed natural to try and preprocess the Pixinsight way. I did it manually for some years, which was incredibly slow, but it taught me a lot about what it’s doing and why. When more recently WBPP was enhanced to its current excellent state it seemed so easy compared with doing it manually that I never thought to compare it with DSS. What I like about WBPP is the way it correctly associates the relevant lights, darks, and flats from a mix of files. Actually, I’ve only ever done OSC, but I can see how useful WBPP might be when dealing with a whole bunch of subs corresponding to different filters and their appropriate calibration files. I really appreciate WBPP’s flow diagrams showing how different files will be processed at each stage because it is very useful when making sure it’s all going to work correctly before hitting the start button. I am interested to hear the thoughts of others on your question. PS. Adam Block’s collection of free YouTube videos entitled the Definitive Guide to WBPP are excellent. They’re split into different aspects like OSC and narrowband. Search for them in YouTube.

Certainly, @LaurenceT. Here in Oxfordshire I decided it was a binocular night. Jupiter and bright stars like Vega were sitting in a halo of glow. Pity because looking at the long term forecast, last night was the only one that offered the prospect of being clear for the foreseeable. 😐

I’ve been watching the weather all day to see if the promise of clear skies as forecast by the Beeb came true. Well, it’s clear in as much as I can see stars, but it’s very hazy. So I decided against setting up and contented myself with a stroll outside with the bins before bedtime. Moon looked good. Night all.

That really is a good capture! Was it really that clear in the early hours? I missed it.