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15+ hours DLSR M45 - bring the dust!


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I never seem to be pleased with my editing of the M45-data I´ve got but now I think I´m getting there! This time I pushed the faint nebulosity even harder but still managed to keep it together... sort

Hej Martin I think it is the time and f/4 unless you have very dark skies. My Sky Quality Meter here on the Swedish countryside usually gives me 21.2 SQM on a moonless night and Ole Alexander in

If you use PixInsight, here's a technique I have used with success (although never on such weak dust; you may spend quite some time on getting the masking right) 1. TGVDenoise in L*a*b mode on L

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I can only agree with everyone else: superb image. Stars, dust, background, it's all spot on. This is definitely not a dead horse, but how would you improve on a winner?

Thanks for sharing

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5 hours ago, Maximidius said:

Super great image Martin, you've done a superb job controlling the stars while showing all of that lovely faint dust. Did you use any darks, bias or flats? and what processing software did you use? 

Thank you! 

To be honest, my memory is not 100% since the stacking was done a while ago but I'm pretty sure I used all calibration frames. At least I used flats and bias frames. 

Calibration, stacking, noise reduction, gradient removal and stretching was done in Pixinsight. Final editing with colour balance, high pass filter and curves in Photoshop. Also a touch of the Astro Tools actions for removal of purple fringing etc.

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9 minutes ago, wimvb said:

I can only agree with everyone else: superb image. Stars, dust, background, it's all spot on. This is definitely not a dead horse, but how would you improve on a winner?

Thanks for sharing

Thank you! Being a bit picky when it comes to my own images I see a lot of things I'd like to improve :)

Most of all the mottled pattern in the darkest parts, typically found in DSLR images when stretching them hard. Don't think I can improve this much more without a cooled mono CCD, though.

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1 hour ago, MartinFransson said:

Thank you! Being a bit picky when it comes to my own images I see a lot of things I'd like to improve :)

Most of all the mottled pattern in the darkest parts, typically found in DSLR images when stretching them hard. Don't think I can improve this much more without a cooled mono CCD, though.

If you use PixInsight, here's a technique I have used with success (although never on such weak dust; you may spend quite some time on getting the masking right)

1. TGVDenoise in L*a*b mode on L only. Use a 50% gray mask and a Luminance mask as support

2. MultiscaleMedianTransform on Chrominance as target. Do this on about 7 layers aggressively. This will kill most mottle, but masking is critical.

I do this in the linear stage.

I've written a more detailed description here:

http://wimvberlo.blogspot.se/2016/07/noise-reduction-for-dslr-astroimages.html

Hope this can be of some use

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1 hour ago, wimvb said:

If you use PixInsight, here's a technique I have used with success (although never on such weak dust; you may spend quite some time on getting the masking right)

1. TGVDenoise in L*a*b mode on L only. Use a 50% gray mask and a Luminance mask as support

2. MultiscaleMedianTransform on Chrominance as target. Do this on about 7 layers aggressively. This will kill most mottle, but masking is critical.

I do this in the linear stage.

I've written a more detailed description here:

http://wimvberlo.blogspot.se/2016/07/noise-reduction-for-dslr-astroimages.html

Hope this can be of some use

Wow, thanks! I will absolutely try that! 

Pixinsight is a jungle. I probably know about 2% of what can be done...

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Amazing image Martin! I agree with all the previous comments.

There is actually so much dust in your image that there are virtually no patches of dark sky. I assume that this is thanks to the 15 hours of data combined with f/4, and great processing of course. This spring I made an effort to bring out as much dust as I could from about 6 hours of M45 data at f/6 (also DSLR but from 5-6" apos) but was still left with some dark patches of sky.

.

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4 hours ago, gorann said:

Amazing image Martin! I agree with all the previous comments.

There is actually so much dust in your image that there are virtually no patches of dark sky. I assume that this is thanks to the 15 hours of data combined with f/4, and great processing of course. This spring I made an effort to bring out as much dust as I could from about 6 hours of M45 data at f/6 (also DSLR but from 5-6" apos) but was still left with some dark patches of sky.

Tack Göran!

Yes, the f/4 and the many hours sure do make the difference. Along with fairly dark skies (but not really dark, like I would want).

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Absolutely cracking image!  At first I thought it was a CCD rather than DSLR.  It has a three dimensional quality to it. I didn't realise the nebulosity appeared so far out from the central stars, or indeed that it had that sort of veil character to it. Well done. 

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49 minutes ago, MartinFransson said:

Tack Göran!

Yes, the f/4 and the many hours sure do make the difference. Along with fairly dark skies (but not really dark, like I would want).

Hej Martin

I think it is the time and f/4 unless you have very dark skies. My Sky Quality Meter here on the Swedish countryside usually gives me 21.2 SQM on a moonless night and Ole Alexander in Norway (who provided 90% of the data for our M45) says his SQM is also around 21. We have some good skies here in rural Scandinavia when the sky clears now and then...

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21 hours ago, gorann said:

Hej Martin

I think it is the time and f/4 unless you have very dark skies. My Sky Quality Meter here on the Swedish countryside usually gives me 21.2 SQM on a moonless night and Ole Alexander in Norway (who provided 90% of the data for our M45) says his SQM is also around 21. We have some good skies here in rural Scandinavia when the sky clears now and then...

No, my skies are probably not as dark as yours. I live in a village with about 30-40 houses so there is some LP.

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