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Xiga

Re-Processing old data - NGC 281

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Posted (edited)

Hi guys

First things first, apologies for posting this one out of season. A combination of no astro dark, crappy weather, and being busy at work has meant that there's no imaging getting done at all these days. So, i've had to turn to old data to re-process, and this data set was an obvious candidate as i was never happy with how it came out originally. And looking back on it now with fresh eyes, boy did it need it! 

Nikon D5300, SW 80ED, HEQ5-Pro. 

3 x 1200s, 2 x 1380s, and 4 x 1500s of Ha
9 x 1200s of Oiii. 
11 x 480s with an IDAS-D1, for RGB stars only
7 Hrs 54 Mins in Total. 


Stacked in APP and processed in PS. 
Combined as SHO (using a 70/30 blend of Ha/Oiii for the Sii). 

The main differences this time were, using Starnet++ to create the starless versions, using more Ha in the synthesized Sii (70% instead of 50% last time), but mostly the improvement has come from toning down the stretch a lot (ok, a heck of a lot!) before making the colour map for the tone-mapping. From then on it was immediately apparent that i'd made a massive boo-boo first time round 🙈

I've included a 1080p rotated crop too, as i quite liked the framing.

Feels like ages since i last did any NB imaging. I almost forgot how much i enjoy it! 🙂 

2121761723_Pac-manNebula(NGC281)SHOv3.thumb.jpg.4167e7168cd5433d2a1096e878d31bfc.jpg

1053699044_Pac-manNebula(NGC281)SHOv31080pCrop.thumb.jpg.6edc58443b8317612879e40dc775b849.jpg

 

 

And rather embarrassingly, here's the original. Try not to laugh too hard! 😂 😂 😂

595994467_Pac-manNebula(NGC281)SHOv2.thumb.jpg.74e0cafb9fc6826da31699a3b30df1c2.jpg

Edited by Xiga
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Very nice result, and there is nothing wrong with the original either.

Carole 

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5 hours ago, carastro said:

Very nice result, and there is nothing wrong with the original either.

Carole 

Thanks Carole.

You're too kind. Either that or it's time for an eye test! 😋

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I really don't know "HOW" you can push your mount to take such long exposures. That is an art in itself.

Then what can i say about your processing, mate i really love what you're able to produce. There aren't many i actively follow but you sir are one of them. (i'm not being kind, i'm being BRUTALLY honest) :) 

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Very nice--I like the original for several reasons--it appears that you used less noise control (may not be true, but it looks that way to me), And the stars look pretty good too, less controlled.  Finally, the outer limits of the nebula are much more prominent in the original--that's why the nebula looks bigger--because it is--especially upward.  Finally, there is less green, which I prefer (except for planetary nebula).  But they are all very nice.

Rodd

 

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On 30/05/2019 at 14:38, souls33k3r said:

I really don't know "HOW" you can push your mount to take such long exposures. That is an art in itself.

Then what can i say about your processing, mate i really love what you're able to produce. There aren't many i actively follow but you sir are one of them. (i'm not being kind, i'm being BRUTALLY honest) :) 

Thanks mate, very kind of you to say ☺️

As for doing long exposures, I don't think it's down to anything special that I do tbh. I just read up on guiding and started doing it, lol. I have to set up from scratch (and tear down) each time I image, which is a pain I have to say! And the mount has had a motherboard replacement too. But aside from that I'm very happy with it. I've done the belt mod, but even before that I found it guided well. My only gripe with it is the payload capacity, as I'd probably need something beefier if I wanted to upgrade to a bigger scope. 

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Posted (edited)
22 hours ago, Rodd said:

Very nice--I like the original for several reasons--it appears that you used less noise control (may not be true, but it looks that way to me), And the stars look pretty good too, less controlled.  Finally, the outer limits of the nebula are much more prominent in the original--that's why the nebula looks bigger--because it is--especially upward.  Finally, there is less green, which I prefer (except for planetary nebula).  But they are all very nice.

Rodd

 

Thanks Rodd. All fair points, and ones I did consider at the time. I'll try to explain my half-baked thinkings 😅

The new version has had a fair amount of colour NR (DSLR NB data really needs it) but you'd be surprised how little Lum NR it's had. The lower stretch meant the the image was just nowhere near as noisy as the original. Of course, as you have rightly said, this means a lot less of the Ha nebulosity is visible in the final image. This was purely a judgement call, i think I really needed a cooled mono camera to push the data further. I think I normally tend to over-stretch my data, so I'm going to try and resist more going forward. I probably over-cropped it too. The data probably can't support a 100% crop too now that I think about it. That might be contributing to the slightly soft/smooth appearance?

As for the stars, I only did a small amount of star reduction. I think what you're seeing is just the effects of the lower stretch, which affected everything, including the stars. 

The issue of green in astro images is one i totally agree with you on, for RGB images. It's taken me a while to realise it, but I now really like leaving a little in there on NB images. Maybe it's because I'm only using 2 filters instead of 3, but I've found that if I nix all of the green then the image tends to look a bit too flat and lifeless to my tastes. But to each their own of course! 😀

 

Edited by Xiga

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15 minutes ago, Xiga said:

I'm only using 2 filters instead of 3

I did not realize this....exceptional work for a bicolor!

Rodd

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With the weather as it is I am wondering whether there is a call for an imaging section v 1.1 where we rework previous data. Might be a good idea to share processing tips on images we have revisited during those cloudy evenings - what went wrong (got that t-shirt) and what worked well (that t-shirt will fit me one day)?

Food for thought.

 

John

 

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Ok one last fiddle. 

I decided to tweak the colours slightly, as i thought it was looking a bit too Ginger and not Gold enough. I also dropped the black slider in the Reds in selective colors to lighten and expand the Ha nebulosity a bit more. 

While i was at it, i also decided to enhance the contrast a bit too (with a High Pass Filter) to try and ease the slightly soft look. I'I also went with a lesser crop too.

Hopefully it amounts to an improvement and i didn't go too far?! 

2038284335_Pac-manNebula(NGC281)SHOv4.thumb.jpg.3f62be6896edc441c5fa4b351238e705.jpg

 

1856562758_Pac-manNebula(NGC281)SHOv41080pCrop.thumb.jpg.e4e0d141113a70cdf8d11fbc82d2026f.jpg

 

 

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