M42 Challenge

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M42 Challenge

Postby Davo » Sat Jan 24, 2015 1:03 pm

Hi all,

I just uploaded my latest M42 to my blog here http://starrydave.com/?p=453

I am very pleased with the way ST teased out the hidden detail and I think I can see some Pillars of Creation type structures as well. Or maybe I am imagining things. Anyway, I am well pleased considering my budget equipment.

Anyhoos, I am still a ST noobie so I would be very interested to see what more advanced users can make from my DSS fits file which is here (124MB)

http://starrydave.com/images/m42.zip

If you can post your results below, I will pinch them for my blog (if Admin don't mind).

Dave
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Re: M42 Challenge

Postby admin » Sun Jan 25, 2015 11:16 pm

Hey Dave,

I had a look at the data, but it appears rather bright for unstretched 20s frames and some modules in ST behaved like the data was pre-stretched. Can you confirm you put the CR2s straight through to DSS without any further stretching in between? What algorithm did you use to stack this?

Thanks!

Ivo
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Re: M42 Challenge

Postby Davo » Mon Jan 26, 2015 10:51 am

Hi Ivo,

My face is burning - I just found out I had loaded the bias frames as flats - my bad.

I reworked the stack in DSS using 90% of the lights. The stacking tab settings were default (I think) as:

Result: Standard mode
Light: Average
Dark: Median with hot pixels removal checked
Bias/Offset: Median
Alignment: Automatic
Intermediate: FITS
Cosmetic: All unchecked

Stacking window is attached with more info

The new FITS file is here.

http://starrydave.com/images/m42a.zip

And my processing attempt is attached. I can't really see much difference from my previous attempt so maybe the bias frames aren't too crucial.

Apologies for snafu
Dave

ps Which option should I select when I first load the FITS file. I have been choosing the left hand button but maybe I should choose the second left?
Attachments
m42all good 90 ST bias bayer jpg.jpeg
m42all good 90 ST bias bayer jpg.jpeg (141.93 KiB) Viewed 1418 times
stacking.jpeg
stacking.jpeg (51.17 KiB) Viewed 1418 times
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Re: M42 Challenge

Postby admin » Wed Jan 28, 2015 1:04 am

Any chance you could stack with Per Channel background calibration also 'no'? If left 'yes' it meddles with the colors and noise levels...
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Re: M42 Challenge

Postby Davo » Wed Jan 28, 2015 11:17 am

admin wrote:Any chance you could stack with Per Channel background calibration also 'no'? If left 'yes' it meddles with the colors and noise levels...


No problem Ivo - it is here

http://starrydave.com/images/m42b.zip

I need to pop out but will gaudify it when I get back.

Dave
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Re: M42 Challenge

Postby Davo » Wed Jan 28, 2015 12:52 pm

Good call Ivo - turning off the per channel calibration made a huge difference. Here is my latest render which looks a lot better, imho.

Dave

m42all good 90 with bias001 resized.jpeg
m42all good 90 with bias001 resized.jpeg (92.5 KiB) Viewed 1385 times
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Re: M42 Challenge

Postby admin » Wed Jan 28, 2015 10:22 pm

Now we're cooking with gas Dave!

Your data looks great now, except for a great number of stacking artifacts all over the place (did you move the scope/camera a lot?). There are some wicked gradients in there though - did you take flats? If not, it should be next on your list!

m42all good 90 with bias001.jpg
m42all good 90 with bias001.jpg (89.19 KiB) Viewed 1379 times


Workflow as follows (in ST 1.4.300)
--- Auto Develop
To see what we got. Much nice data now, but lots of stacking artifacts. Bad gradients too. Some oversampling.
--- Bin
To convert oversmaplping into noise reduction (this data could be good enough for some serious decon! :twisted: )
Parameter [Scale] set to [(scale/noise reduction 50.00%)/(400.00%)/(+2.00 bits)]
--- Crop
Trying to visualise and get rid of stacking artifacts.
Parameter [X1] set to [786 pixels]
Parameter [Y1] set to [200 pixels]
Parameter [X2] set to [1981 pixels (-164)]
Parameter [Y2] set to [1417 pixels (-11)]
--- Wipe
Did a wipe, but found more stacking artifacts to the right. (cancel, undo)
--- Crop
Parameter [X1] set to [0 pixels]
Parameter [Y1] set to [0 pixels]
Parameter [X2] set to [1078 pixels (-117)]
Parameter [Y2] set to [1217 pixels (-0)]
--- Wipe
Wipe again.
Parameter [Aggressiveness] set to [83 %] to better deal with the wicked gradient.
--- Auto Develop
Final global stretch. Used ROI over central M42.
Parameter [Ignore Fine Detail <] set to [3.6 pixels]
--- Deconvolution
Parameter [Radius] set to [4.2 pixels]
Good bit of extra detail, especially in the core. Nice! Binning helped, increase the SNR, allowing Decon to dig out more.
--- Wavelet Sharpen
Using same mask decon made.
Default parameters.
--- Color
Came up with a good color balance all by itself.
Parameter [Dark Saturation] set to [3.70] to introduce a little more saturation in the darker parts.
--- Wavelet De-Noise
Note parameters are 1.4.300 specific.
Parameter [Grain Size] set to [11.5 pixels]
Parameter [Smoothness] set to [83 %]
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Re: M42 Challenge

Postby Davo » Thu Jan 29, 2015 11:29 am

You are the man Ivo :bow-yellow:

I am sitting here looking at your version against mine above (which I thought was pretty good) but it's chalk and cheese. There is just so much more detail and things to look at. Amazing.

The fits file was a composite of 4 separate imaging runs over the same evening. You can see I am having trouble with tracking my HEQ5 Pro which is why there are so many artefacts on each side. I will take some flats for my next run but we have 6cm of snow here just now so it might be a while.

Thanks for taking the time to talk me thru the process and I am going to try and recreate it. Funnily enough, I got a deep sky imaging book for xmas and I am now on the decon chapter so I will give it a try as well.

To me, your version epitomises what is great about your software. I can use an entry level, un-modded DSLR on a cheap, un-guided scope and get a great image.

Dave

ps The book I am reading says that alt-az mounts cannot be used for deep sky. I am very tempted to mount my 4SE on its original mount and prove him wrong with DSS and StarTools.
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