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x6gas

M81 and M82

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As part of the re-learning process I'm going through, I've had an attempt at M81 and M82 which was inspired by Adam's (tooth_dr) image posted just after Christmas.

I just couldn't seem to get the processing right on this one which surprised me because I think the data is decent. To be fair, a lot of this is because I have forgotten how to interpret what the data is telling me and use that to inform my processing choices but I had to abandon my usual colour combine in Photoshop and use AstroArt for that instead. 

The first version below uses something close to my standard workflow; I'm really careful not to introduce noise and this dropped out without too much drama but I wasn't happy with the richness of the star field.

The second version is the eighth iteration of the fourth reprocess!  I really struggled to control colour noise that was being introduced in this one as I tried to boost the saturation and used multiple iterations (literally six or seven) of Rob Gendler's LLRG method to keep the noise down and was using star masks, star layers and basically every trick I could remember.  I must confess that I blended the galaxies from a different version into this as M81 was coming out a bit green...

Data: L: 22 x 300s (binned 1x1); R: 22 x 180s (2x2); G: 20 x 180s (2x2); B: 20x 180s (2x2); 30 darks and 100 flats for each channel.

Kit: Scope: FSQ85; Mount: CEM60ec; Camera: Atik 460ex; Filters: Astrodon; Guiding: Atik OAG, QHY5L-II, PHD2

I've always found comments from SGL members to be hugely helpful in pointing my processing in the right direction so please do let me know what you think about these two versions...

Clear skies, Ian

M81 M82 Final v1 1200px.png

M81 M82 LLRGB v8 1200px.png

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I think I prefer the first one! :D

Yes, there's slightly more detail in the second one, but the stars are a bit too starry for me.

I get more of a feel of depth and distance and the vastness of space from the first.

But don't let that worry you, they're both great and I know nothing about astrophotography! ;)

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52 minutes ago, x6gas said:

As part of the re-learning process I'm going through, I've had an attempt at M81 and M82 which was inspired by Adam's (tooth_dr) image posted just after Christmas.

I just couldn't seem to get the processing right on this one which surprised me because I think the data is decent. To be fair, a lot of this is because I have forgotten how to interpret what the data is telling me and use that to inform my processing choices but I had to abandon my usual colour combine in Photoshop and use AstroArt for that instead. 

The first version below uses something close to my standard workflow; I'm really careful not to introduce noise and this dropped out without too much drama but I wasn't happy with the richness of the star field.

The second version is the eighth iteration of the fourth reprocess!  I really struggled to control colour noise that was being introduced in this one as I tried to boost the saturation and used multiple iterations (literally six or seven) of Rob Gendler's LLRG method to keep the noise down and was using star masks, star layers and basically every trick I could remember.  I must confess that I blended the galaxies from a different version into this as M81 was coming out a bit green...

Data: L: 22 x 300s (binned 1x1); R: 22 x 180s (2x2); G: 20 x 180s (2x2); B: 20x 180s (2x2); 30 darks and 100 flats for each channel.

Kit: Scope: FSQ85; Mount: CEM60ec; Camera: Atik 460ex; Filters: Astrodon; Guiding: Atik OAG, QHY5L-II, PHD2

I've always found comments from SGL members to be hugely helpful in pointing my processing in the right direction so please do let me know what you think about these two versions...

Clear skies, Ian

M81 M82 Final v1 1200px.png

M81 M82 LLRGB v8 1200px.png

I cannot give any meaningful comments Ian, I have always been visual only, however, I think they are beautiful.:smiley:

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A very good job.  Well done.

M81 has a very wide dynamic range with its very bright core and fainter arms, which means many pictures show the core overexposed with respect to the spiral arms.  M81, M31 and M42, despite being amongst the most popular targets and easy to capture are infact some of the most difficult to process because of this very High Dynamic Range (HDR).

Investigate tools such as PixInsights HDR Multiscale Transform tool.

https://www.lightvortexastronomy.com/tutorial-producing-an-hdr-image.html

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7 hours ago, bingevader said:

I think I prefer the first one! :D

Yes, there's slightly more detail in the second one, but the stars are a bit too starry for me.

I get more of a feel of depth and distance and the vastness of space from the first.

But don't let that worry you, they're both great and I know nothing about astrophotography! ;)

Thanks Ben. Now I come back to them the background in each looks a bit light.  I think I know what you mean about the stars in the second one.  As is so often the case I think the idea process is somewhere in between!

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7 hours ago, Saganite said:

I cannot give any meaningful comments Ian, I have always been visual only, however, I think they are beautiful.:smiley:

Thanks Steve - appreciate the comment ?.

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7 hours ago, kirkster501 said:

A very good job.  Well done.

M81 has a very wide dynamic range with its very bright core and fainter arms, which means many pictures show the core overexposed with respect to the spiral arms.  M81, M31 and M42, despite being amongst the most popular targets and easy to capture are infact some of the most difficult to process because of this very High Dynamic Range (HDR).

Investigate tools such as PixInsights HDR Multiscale Transform tool.

https://www.lightvortexastronomy.com/tutorial-producing-an-hdr-image.html

Thanks kirkster.

I started this capturing 600s luminance subs but the core of M81 was badly blown out which is why I dropped the exposure time down.  I could have processed it with less brightness in the core but this felt about right to me.  I'd captured M81 by itself using my Edge several years ago and this process was influenced by that...

One of the things that has changed while I've been away is the prevalence of PixInsight.  It was around but, IIRC, not that widely used - I guess because of the reputed steep learning curve - but it seems much more popular now.  So the HDR processing in this was used with traditional layer masking in PS... though AstroArt does have its DDP it doesn't really give the control I need... unless I am using it incorrectly which is probably the case!

So I must give PixInsight a go... but I want to make sure I have plenty of time available during the trial period to properly evaluate it so it may be a while!

Thanks again.

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Very good images Ian.  The second has resulted in IMHO more detail within the two galaxies.

The size of the stars is a distraction from the spelndid detail in the second image - have you tried some star reduction?  The first image's stars are perhaps too tight - did you sharpen the stars by any chance?

If you could combine the second image's galaxies with a blend of the two star fields you could then make another assessment.

HTH

Barry

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6 hours ago, Barry-Wilson said:

Very good images Ian.  The second has resulted in IMHO more detail within the two galaxies.

The size of the stars is a distraction from the spelndid detail in the second image - have you tried some star reduction?  The first image's stars are perhaps too tight - did you sharpen the stars by any chance?

If you could combine the second image's galaxies with a blend of the two star fields you could then make another assessment.

HTH

Barry

Thanks for the feedback Barry.  Nope, no sharpening of the stars in the first image.  It's just a very conservative stretch of the stars and background in that image.  I blended in a harder stretch of the galaxies.

I didn't try star reduction - any tips or pointers to tutorials?

Now, funny story, after posting these (and bearing in mind that I spent hours processing the second image) I just did a couple of stretches of the first version and it resulted in a nice compromise between these versions... and took about two minutes!  However, I had been rather careless in the transition between the galaxies and the background so I need to re-run the process but I think there is a middle way with this one!

Thanks again for the feedback; it really helps.

Clear skies, Ian

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On 09/02/2019 at 17:30, x6gas said:

So I must give PixInsight a go... but I want to make sure I have plenty of time available during the trial period to properly evaluate it so it may be a while!

 

I tried Pixinsight a long time ago and as like you found it overwhelming so I tried AstroPixelProcessor, it might not have all the bells and whistles but using the default settings produced for me an image I could then put into light room and get a reasonable image.

I like the second one for the detail but the background is a bit too light on my screen.

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2 minutes ago, Mark Haythorne said:

I tried Pixinsight a long time ago and as like you found it overwhelming so I tried AstroPixelProcessor, it might not have all the bells and whistles but using the default settings produced for me an image I could then put into light room and get a reasonable image.

I like the second one for the detail but the background is a bit too light on my screen.

Thanks Mark.  This is also really helpful.

I do seem to be keeping the background too light!  Back in the day I'd settled on a standard value for the background - I should really go back and find out what it is - but right now a value of 30 seems OK whereas I think on this image it's 40 or 50.  I've forgotten a lot but it seems pretty obvious that I should set the background to a certain value rather than wing it!

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