Iris with Ghost and friends in Nautical Darkness

[symmetal]

Due to trees to the North I can only see these in the Summer from my fixed pier so thought I'd give them a go as I was impressed with gorann's similar view posted last month with all the extra dusty features. I didn't expect too much but imaged it over 4 nights waiting until 45 mins after nautical dark to start, so got around 2.5 hours a night.

FLT98 with ASI6200, Astronomik Deep Sky RGB and L3 luminance filters. 1.9 hours each of RGB and 4.6 hours of L so 10.3 hours total. Stacked in APP and processed in Startools binning 50%, and finished off in PS. I was pleased with the result, although not much colour detail in the dusty bits. Can't really compare with gorann's 15 hours with a RASA 8 though 😁

Click for full size and thanks for looking. 🙂

Alan

[Stuf1978]

Nicely done, looks great

 

[symmetal]

Thanks Stuf1978 and the others. 😀

I found using a higher dither setting helped greatly in reducing the coarse background noise mottling leaving just a fine noise which is less noticeable. While Startools noise reduction does reduce background noise without affecting the subject detail it still gives an obvious noise reduced look so I don't use it. I found the Nik Define2 plugin for Photoshop gives more 'natural' looking noise reduction so I used that and just layered the Iris centre without noise reduction on top.

There are two galaxies in the image though one is hard to spot without knowing where it is. 🙂

Alan

[carastro]

That's come out really well.  I expect you have nice dark skies normally from your location.

Carole 

[symmetal]

11 minutes ago, carastro said:

That's come out really well.  I expect you have nice dark skies normally from your location.

Carole 

Thanks Carole.  That certainly helps. It is classed as Bortle 2 or 3 depending on definitions. I measured 21.1 with the SQM meter in the middle of the nautical darkness period.

Alan

[jager945]

Great image - so much to see and the objects of interest stand out well. 👍

This area is deceptively difficult to process, with so much "dark" dust. You have managed to (correctly) look like the dark dust is in front of the background rather than part of it. Excellent!

10 hours ago, symmetal said:

While Startools noise reduction does reduce background noise without affecting the subject detail it still gives an obvious noise reduced look so I don't use it.

Then you are unfortunately missing out on one of the most important and powerful bits in StarTools. 😔 You should obviously tweak the result to taste, and for your tastes - most likely - the parameter you're looking for is the "Equalized Grain" parameter.

It reintroduces noise grain back into the denoised result, however in such a way that its perceived magnitude is equal in all areas. E.g. it makes your image look as if it has a fixed SNR across the entire image, regardless of how you stretched or locally processed it. This leaves your image with the type of residual noise signature that terrestrial photographs possess and is often considered "pleasing" noise (CGI often artificially introduces this sort of noise to come across more convincing). If that is not what you're after then there are a myriad of different ways to shape residual noise grain (the module is a noise grain shaper, which as the name suggest, lets you shape the grain in any manner you please).

Being able to use and control StarTools's Denoise module effectively will be even more important in the upcoming 1.8 version, as it will be - more than ever - a vital part of getting the most out of the new deconvolution module and, by extension, your hard-won signal.

Any trouble, questions, do let me know!

[symmetal]

Thanks Ivo. Much appreciated. 😀

12 minutes ago, jager945 said:

Then you are unfortunately missing out on one of the most important and powerful bits in StarTools. 😔 You should obviously tweak the result to taste, and for your tastes - most likely - the parameter you're looking for is the "Equalized Grain" parameter.

Ah! that's interesting. Before I used the higher dither setting the coarse blocky background 'mottle' noise was more noticeable than the fine noise and the Startools noise reduction removed the fine noise well, and so made the mottling more apparent. The grain size parameter had to be set high to start combatting the mottle which gave the results a plasticky look. I did tinker with the 'Equalized Grain' but not properly. As you say, some fine noise in an image makes it more 'natural' and also gives the effect of it looking sharper. I'll give it another go and see how I get on. I'll pay the de-noise module more attention. 🙂

I look forward to seeing what version 1.8 offers.

Alan

[symmetal]

Here's it reprocessed again using the Startools noise reduction as @jager945 recommended 😀. The 'Equalized Grain' added noise did give a more natural look to the image, though I also found reducing the de-noise wavelet Scale 1 to 85% and the Scale 2 to 90% left some residual fine noise in the image and so less Equalised Grain was needed, and 5% Equalized Grain kind of filled in the gaps in the residual noise that was left. The overall result was extra detail revealed in the dust which wasn't readily visible in the non de-noised version and which the Photoshop Define2 denoise had removed. I've also added a crop of the Iris itself showing the three noise methods. They're high quality jpegs, so some artefacts are present but the general difference is seen.

It's down to personal taste how much de-noiseing you prefer of course. 🙂

 Full image. Click for full size.

No de-noise

Startools de-noise: 3.0 pixel grain size, 85% Scale-1, 90% Scale-2, 5% Equalized Grain

Photoshop define2 de-noise. On the original I did overlay the un de-noised Iris core back in.

The only problem now is I have to go and re-process my older images. Thanks Ivo. 😁

One final question Ivo, on the Binning module you have 4 pre-defined presets of 25%, 35%, 50% and 71% binning. The 25 and 50 are obvious, but is there an advantage of choosing 35 or 71 over say 33.3 or 66.6 which might seem more intuitive numbers. I notice 35% (actually 35.38%) is the square root of 1/8, and 71% (actually 70.71%) is the square root of 1/2, so there may be a clue there. 🙂

Alan

 

[jager945]

3 hours ago, symmetal said:

The only problem now is I have to go and re-process my older images. Thanks Ivo. 😁

One final question Ivo, on the Binning module you have 4 pre-defined presets of 25%, 35%, 50% and 71% binning. The 25 and 50 are obvious, but is there an advantage of choosing 35 or 71 over say 33.3 or 66.6 which might seem more intuitive numbers. I notice 35% (actually 35.38%) is the square root of 1/8, and 71% (actually 70.71%) is the square root of 1/2, so there may be a clue there. 🙂

Great to hear it helped and is making a great image even better.

You are indeed correct about the square root If you try the different presets, you should notice the amount of extra bits (e.g. increased precision in the dataset) going up by whole integers.

Do let me know if you'd like a 1.8 preview (which has some improvements/ tweaks to Denoise) - I can send you a private link.

Clear skies!

[symmetal]

12 hours ago, jager945 said:

Great to hear it helped and is making a great image even better.

You are indeed correct about the square root If you try the different presets, you should notice the amount of extra bits (e.g. increased precision in the dataset) going up by whole integers.

Do let me know if you'd like a 1.8 preview (which has some improvements/ tweaks to Denoise) - I can send you a private link.

Clear skies!

Thanks Ivo for the explanation. I'd be very happy to try the 1.8 preview and see what extra goodies it has. Much appreciated. 😀

Alan