Ngc 6744

[xelasnave]

RASA RBG and L ...4 hours at 30 sec 100 gain terrible seeing but what do you do? A great experience with the Asiair plus.

A great exercise in making a silk purse out of a pigs ear, except it is not a silk purse:P...and I know its noisey but you should have seen it earlier...

I actually am very happy as I got some control on the colour and really you should have see the stacks all you could see of a galaxy was a smudge...


alex

[oska]

Interesting. I'm intrigued as to what/where/why that green comes from?

[xelasnave]

From all the trees around the observatory;)...I thought I was on top of it ..my daughter helped ...hmmmm maybe I posted the wrong image as I had a couple of finals and she said some were very green...anyways I am gathering more data so I will see how things develop.
Alex

[Crater101]

Oddly enough, recently I was making an (unsuccessful) attempt at a capture from the middle of a disused cricket pitch not far from where I live, and had a red cast through all my images. Couldn't work out why.


In a classic case of always look behind you, it turned out that about a hundred metres away there's a railway line, which had a red signal on the line. Despite it being reasonably shielded by the housing, there was enough of it to affect what I was doing.

[xelasnave]

One needs a good collection of explanations;)

Alex

[oska]

Alex, do you by any change have a green laser pointer? I noticed one of my subs a while back copped green thing (but I deleted it in a mad cull frenzy) and now I suspect at least for me it was from the laser pointer I have mounted to the rig. I use it to navigate around the many trees here.

[xelasnave]

no laser.

I added some Ha but I dont know about the colour
I added ha with my lum:P

[oska]

Bugger, still intrigued.
That Ha stepped it up a notch ;)

[RB]

:lol:

[xelasnave]

Longer time means more tree green

[xelasnave]

These images are Luminance,Red, Blue and Green { HA was added to build the luminance stack
].... all are in effect mono...the colour comes in when in "combine" in Startools...Each go in a box LUM, RED GREEN BLUE and in that module you cant adjust the colour ..says you can but I cant at least .. I tried when in the colour modual. I back off the green but too much and everything goes purple...and I try watching the graph and even when they all overlay it is any bodys guess... then in photoshop I SELECT hue and saturation ..select green and turn down the saturation.

so that proves it is the trees;):lol::lol::lol:
alex

[Dave882]

Nice one Alex- it’s tricky adding Ha but I like the result. :thumbsup:

[xelasnave]

Thanks..still so much wrong...but things must get better.

My stars were oval and I over compensated...but there seems to be so many stars I would like to try to get rid of most of the...mmm another time onto something else...

Alex

[Startrek]

Alex,
A fine Galaxy image with all things considered
Pavo Galaxy does have an immense Star field , most other galaxies have sparse Star fields but this one is unusually dense
In Startools you can manage or reduce the dense Star field using a few things like -
Shrink ( use a Star mask ) where stars are green or sampled
Super Structure ( dim small preset ) use an inverted Star mask where stars are unsampled or normal
Super Structure ( isolate preset ) use an inverted Star mask where stars are unsampled or normal

Cheers
Martin

[xelasnave]

Thanks Martin..I don't seem to get much of a shrink with shrink...
I just changed to the OSC and no filters I think that may help star size I don't think the RASA responds very well to filters so it will be interesting...if nothing else no riding around on my lawnmower in the middle of the night changing filters...thanks for your encouragement, help and kindness.

Alex

[Startrek]

That’s really strange Alex
I can shrink my Stars down to tiny specs if needed
In fact I normally have to back off the default setting of 10 down to 6 as it tends to be too aggressive
You have to make sure you have a good Mask in place ( which is easy ) as well and ensure the whole stellar structure of the Star is sampled or green
Also definitely try Super Structure ( Dim Small and Isolate ) they work beautifully for me as well
I can provide a sample workflow if your at all interested ??

Cheers
Martin

[xelasnave]

Thanks Martin ..yes I am always interested in any information on StarTools.
You may like 5o know I have been running my gain at 100 but the last run at 0
Alex

[Startrek]

No problem
I’ll send you some info on the use of Shrink and Superstructure ( Dim small and Isolate ) soon. Glad to help in any way I can

In regard to Gain on the 2600MC and 2600MM, the ZWO performance charts say it all.It’s best using Gain 0 only for long exposures ( 5min + ) in darker skies where you can take advantage of the huge full well capacity of 50k
For your short exposures ( 30 sec and similar ) Gain 100 is preferable as read noise is only 1.5e whereas Gain 0 is 3.5e , a huge increase in read noise.
At Gain 100 you still have 20k of well depth with excellent dynamic range up to 13.5 stops
Gains higher than 100 , say 300 to 350 don’t achieve any significant read noise reduction than Gain 100 , however you do lose dynamic range and well depth
I’d experiment with Gain 100 and Gain 300 , but forget Gain 0 using short exposures of 30 sec and similar, your not achieving anything ( even under dark skies )

Cheers
Martin

[xelasnave]

Thanks Martin..put me down for a copy of your book.

Yes now I have auto guide via Asiair plus I may give some long exposures a go if I ever get some decent sky...like the best I have had is such that once I just would not have bothered...in fact the main reason I ga e it away years ago was this level of moisture...the observatory just gets so wet I find it demoralizing...

Good news my news wheels are at the Post Office..but the damn Arduino starter kit is all just parts build it yourself which I could handle but no diagram or instructions...done my money unless I can find out how to build it.
Anyways so busy I can't address that now.


Alex

[Startrek]

Alex,
Attached is my image of NGC 6744 Pavo Galaxy captured down south from my Dome with the 10” Carbon fibre Newt and EQ8-R mount
5 min subs at Gain 0 ( 3 hours of data with calibration frames Flats and Bias )

The 4 images show the progression in processing with Startools 1.8 from original untouched Star field to using Shrink ( tighten ) , then Dim Small ( Superstructure) then Isolate ( Superstructure)

Also attached is a photo of my Star mask I used for all Star reduction processing

You see a massive reduction in Star brightness from original to final

I’ll post a separate workflow for a Star Mask , Shrink , Dim Small and Isolate

Oh just a question which version of Startools are you using , hopefully version 1.7 or the latest version 1.8 ?

Cheers
Martin

[Startrek]

Alex,
Workflow for creation of good Star Mask and using Shrink , Dim Small and Isolate ( Superstructure) to reduce Star field in Startools v1.7 or v1.8

Star Mask

NB: As stars are made up of many pixels , undersampled data , heavy binning or heavy cropping will reduce resolution and therefore reduce the number of pixels that make up a Star. This will have a knock on and negative affect in creating a good Star Mask as Stars will end up blocky when you zoom in making it impossible to ensure a good round Star Mask covering the whole stellar profile of the Star.
If your image scale is oversampled ( below 1 arc sec per pixel ) which is ideal then recommend Cropping edges only and maximum Bin 50%

Press Mask at top
Then press Auto
Set Filter Sensitivity to 1
All other settings default
Press Do
Basic Star Mask appears

Note 1: Any stars not sampled or green can be masked by setting Brush Mode below to “Flood Fill Lighter Pixels “ and then click on Star core white pixels to start mask and click on white pixels just outside green mask to expand mask.
Alternatively you can use Brush Mode “Lasso” and draw mask around Star
Note 2 : Any small or tiny stars not fully masked , just use the “Grow” button at the top. One click at a time. If you grow too big use the reverse button “Shrink”

Important !!!
Ensure the whole Star is masked out green , slightly overlapped the better



Shrink Module

To be used after main processing just before Colour module and final noise reduction

Make sure you have a good Star Mask set with all stars sampled or green

Select Shrink
Shrink may ask you to set a Star Mask , select “Keep Mask as is “
Ensure Mode setting is set to “Tighten”
Adjust iterations from default 10 up to 20 and use before and after button to inspect Star size and brightness reduction
All other settings leave as default

NB: If Stars have large than normal halos use Uni glow Strength and Uni glow Kernel sliders below to reduce halos
Once satisfied with Star field press Keep




Superstructure Module ( Dim Small and Isolate presets )

Can be used after Shrink and either before colour or after colour module and before noise reduction

Make sure you have a good Star Mask set with all stars sampled or green. Then press “Invert” at top so that stars now are “not sampled” white and background is green or sampled
Press Keep

Now select Superstructure Module
Superstructure may ask you to set a Mask, select “Keep Mask as is”
Then press “Dim Small” preset at top.
The only slider to adjust will be “Strength” Default is 100%
NB: Don’t increase past 100% only reduce down to 90, 80 , 70 , 60 to 50%
Once satisfied with the Star field reduction press Keep

Further Star reduction ( Optional ) is “Isolate”
Select Superstructure module again
Keep Star Mask as is
Select “Isolate” preset at top
Reduce “Strength” from default 100% down to at least 50% or 40% as this feature is quite aggressive
Once satisfied with Star field reduction, press Keep

Now select Star Mask at top again and press “Clear” then “Keep”

Star reduction is now completed !!

Your now ready to finalise your processing using Colour and then final Noise Reduction


Hope the above helps

Cheers
Martin

[xelasnave]

Thanks Martin
With the new computer StarTools was only loaded three days ago so it would be the latest...I am not sure with the lap top but ( cant look at it right now) but it would be within the last 12 months.
Alex

[xelasnave]

Martin Thank you very much for the work flow as I just relied on the "create a mask" tool and thinking about it taking more time should be worth it.

Because I crop heavily I don't bin..I dont know if that is advisable?


I am putting in another tri pier system today so finally all three scopes will be on solid bases.
Things are finally coming together..two Asiair plus have been shipped, new wheels are here and I think I have licked the dual winch drum issue..the Arduino however was just a box of parts with no instructions so I will order another and some relays...

Thanks again...can you do anything about the weather please;)

Alex

[Startrek]

Alex,
Always glad to help ( where possible)
Wet in Sydney too
Maybe an Aztec Sun dance might help ?
In regard to your image size and a Star Mask my native size off DSS when loaded into Startools is around say 6500 x 4500 pixels and after I crop edges for stacking artefacts and either a 50% to 60% Bin ( don’t forget you can use the slider to adjust Binning and not just rely on the presets up top ) that gets me down to around say 4800 x 2800 pixels which is excellent for a good Star Mask
Just remember it’s all about sampling with the number of pixels
I’m oversampled with my newts and 2600MC ( 0.86 to 0.42 arc sec per pixel ) so I have ample pixels to cull my image size down without my Stars looking really “blocky” when you zoom in a bit
Using your RASA 11 and ZWO 2600 cameras your image scale or sampling will be 3.76uM x 206.3 / 620mm focal length = 1.25 arc sec per pixel . So your bordering on being undersampled which makes it difficult. It all depends on your final image size
A quick check is to zoom in to 100% and if your Stars look roundish not blocky then the image size is good and a Star mask will work well for Shrink and other modules
I can zoom in to 200% or even 300% and my Stars still look roundish

Setting up my image size and resolution is the first thing I check and of course noise floor as well , before I jump into real processing with AutoDev, HDR , Sharpen and so on ….

I was going to talk about the new Deconvolution ( SV Decon ) in version 1.8 but I’m still having a few issues with it . It needs well oversampled data and quality data to work well. I’ve been posting stuff on the Startools forum and Ivo has been most helpful ….., but that’s for another day

Cheers
Martin

[xelasnave]

Very heavy rain here such that we stopped work but have three holes and all star pickets in ...
I have tried to join StarTools forum..they acknowledged my application and said I would receive an email when approved but it never came..I guess they know me there;)

Thanks again Martin.

Alex