M42 Challenge

[Davo]

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

[admin]

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

[Davo]

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?

[admin]

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

[Davo]

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

[Davo]

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 (92.5 KiB) Viewed 11286 times

[admin]

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 (89.19 KiB) Viewed 11280 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! )
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 %]

[Davo]

You are the man Ivo

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.