Star bloat with 294mc pro

[AstroNebulee]

Hi

I know this issue has been covered a lot on this forum and others but I've not seen anything quite concise enough.  I still suffer with quite a bit of star bloat in my images dispite using my ir uv cut filter.  My imaging area is a rural bortle 3 (don't like using bortle scale) and dont suffer with very uch LP.  My goto imaging settings are 180 sec subs 120 gain and -10 degrees .
Now I've been thinking is my zwo filter the cause of the boat? 
Would it be better not using it at all?
Are there any better ir uv cut filters?
Does anyone using the same setup have any feedback or advice.
I cannot afford any further purchases at this point after losing money due to covid isolation. 
My set up is:
Sw 72 ed (not short tube version)
Az Gti eq mode
zwo asi 294 mc pro imaging camera
zwo asi 120 mc-s guide camera with zwo 30mm guidesscope
Asi Air Pro
Ovl FF
zwo 2 inch ir uv cut filter
I can process some of the issues of it to help or am I just losing my mind and they aren't that bad.

 

Cheers

Lee

 

Edited April 18, 2022 by AstroNebulee

[Clarkey]

You could consider an L-3 filter which narrows the spectrum down a bit. Also, look at your processing, you may be able to reduce the stars with slightly different methods. 

[AstroNebulee]

1 hour ago, Clarkey said:

You could consider an L-3 filter which narrows the spectrum down a bit. Also, look at your processing, you may be able to reduce the stars with slightly different methods. 

Thank you, I have been recommended the L3 before for the CA in my system too, I shall research it more. 

What are your thoughts on the optolong L-pro as a comparison to the L3 as it is uv ir blocking capabilities? Just think the zwo isn't the greatest quality despite being matched to the 294mc pro. I can go back into gimp and reduce and tighten the stars a tad more with erode or in ps with the minimum filter. I believe my processing is getting better each time and learning more everyday with it. 

Hopefully others with my set up or close to it have solved this. 

Edited April 18, 2022 by AstroNebulee

[Clarkey]

I think the L-pro is more of a light pollution filter which in bortle 3 you don't need. The L-3 cuts down on the total at the blue and red ends. This will be more suitable for removing blue bloat. I managed to get away without it for my ED80 so I have not direct experience, but purely looking at the spectrum the L-3 definitely looks like the better option for you. The L-pro removes sodium and mercury vapour lines so cuts down on multiple wavelengths,

[AstroNebulee]

53 minutes ago, Clarkey said:

I think the L-pro is more of a light pollution filter which in bortle 3 you don't need. The L-3 cuts down on the total at the blue and red ends. This will be more suitable for removing blue bloat. I managed to get away without it for my ED80 so I have not direct experience, but purely looking at the spectrum the L-3 definitely looks like the better option for you. The L-pro removes sodium and mercury vapour lines so cuts down on multiple wavelengths,

Thank you Clarkey, much wgat I was thinking with regards to which filter to head to when funds allow. 

The zwo does a job but not the greatest when you compare to the L3 and hopefully will get to see soon.

Just on a side note the optolong ir uv cut filter seems like it cuts more ir uv than the L3 does, ddo you have any thoughts on that one. 

Cheers 

Lee 

Edited April 18, 2022 by AstroNebulee

[AstroNebulee]

Something just pinged in my brain whilst having a think (it doesn't happen often haha) does it matter where my ir uv cut filter is placed on my imaging train? 

Atm my imaging train is 

Scope - then ir uv filter in the skywatcher rotator - ovl FF-spacers - tilt adjuster - 294mc pro. 

Does it make any difference if the filter is before or after the FF?

Cheers 

Lee 

[Budgie1]

I've always put any filter right in front of the camera sensor, so it's the last thing the light passes through before it hits the sensor. Whether this makes any difference, I don't know, but it works for me.  

I have the 2" ZWO UV/IR cut filter and I've just replaced it with the L2 for use with my ASI294MC Pro in Bortle 2. I've not really had time to see if it makes a difference as I've only had a couple of clear nights when I've used it, but the last image is below. Mine is connected to SW Evostar 100ED DS Pro with a 0.85 FR/FF.

How do you check your focus? I only ask because the image of the Rosette looks a bit out of focus, when looking at the dust, bottom right of centre, and this will effect star bloat as well. 

Processing can also have an effect, like over stretching the image trying to wring out that last bit of data. If you want to post one of your stacked files, I can put it through my normal work flow in PI to see what it looks like.

[AstroNebulee]

8 hours ago, Budgie1 said:

I've always put any filter right in front of the camera sensor, so it's the last thing the light passes through before it hits the sensor. Whether this makes any difference, I don't know, but it works for me.  

I have the 2" ZWO UV/IR cut filter and I've just replaced it with the L2 for use with my ASI294MC Pro in Bortle 2. I've not really had time to see if it makes a difference as I've only had a couple of clear nights when I've used it, but the last image is below. Mine is connected to SW Evostar 100ED DS Pro with a 0.85 FR/FF.

How do you check your focus? I only ask because the image of the Rosette looks a bit out of focus, when looking at the dust, bottom right of centre, and this will effect star bloat as well. 

Processing can also have an effect, like over stretching the image trying to wring out that last bit of data. If you want to post one of your stacked files, I can put it through my normal work flow in PI to see what it looks like.

Hi Martin

Thank you for your reply.  I  may see if I can swap the position of my filter around but I have seen many others put the filter in the rotator before but as you say there maybe no hard and fast rule.
Can I ask why you chose the L2 over the much suggested L3?
I check my focus prior to imaging after my polar alignment and before I commence imaging my target using a batinov mask.  I suspect the blurring is from using the de noise module in Startools and then a slight further noise reduction in ps.

I will attach a tiff and fit file of the said Rosette image that I have cropped out the stacking artefacts in siril but no other processes.
I do think though that my 72ed hasn't the best optics and is the poorer cousin of the 80ed and above in the sw ed range, even though is a apo doublet just poorer glass, so this wont be helping the bloating and ca I get. I've seen it on other images with a 72ed too.

 

Cheers

Lee

Rosette combined crop.tif Rosette combined crop.fit

[AstroNebulee]

I have a go at reducing the bloat in ps quickly this morning and have reduced the bloat a bit more.

 

 

 

 

Edited April 19, 2022 by AstroNebulee
added edoted image

[alacant]

52 minutes ago, AstroNebulee said:

reduced the bloat a bit more

Hi

I don't think there's anything wrong with the hardware. If anything, it could be not so good tracking or guiding; you still get round stars, but fatter. Maybe go easy on the smoothing/denoise or whatever ps calls it?

But hey, there's some lovely detail.

HTH

 

 

[AstroNebulee]

21 minutes ago, alacant said:

Hi

I don't think there's anything wrong with the hardware. If anything, it could be not so good tracking or guiding; you still get round stars, but fatter. Maybe go easy on the smoothing/denoise or whatever ps calls it?

But hey, there's some lovely detail.

HTH

 

 

Hi Alan

Thats a superb process you got there. Did you use the autodev feature in startools to get the stars that tight, I used film dev on the first process and just now tried autodev, its all a big learning curve trying to balance the noise with the autodev and not with film dev. I will try again with less noise reduction.  Would it be possible to post your workflow so I could get a few ideas?

Thank you.

 

Lee

Edited April 19, 2022 by AstroNebulee

[alacant]

6 hours ago, AstroNebulee said:

I used film dev

Ah, OK. That's designed to make it look like old film processing. Of course, that's maybe what you're after. 

If you want something less 'filmy', try AutoDev throughout, with as many ROIs as is necessary to get the effect you want. 

Here are three alternatives. All have the stars under control. Only one will get you on the road to the current perceived norm;)

HTH

     

Edited April 19, 2022 by alacant
translation

[AstroNebulee]

2 hours ago, alacant said:

Ah, OK. That's designed to make it look like old film processing. Of course, that's maybe what you're after. 

If you want something less 'filmy', try AutoDev throughout, with as many ROIs as is necessary to get the effect you want. 

Here are three alternatives. All have the stars under control. One will give you the current perceived norm;)

HTH

     

Thank you Alan, I have given it a go with just autodev and came out with these 2 results (one with no purple halo reduction in ps) will work on it and use less noise reduction. Also another idea maybe to not set a ROI in autdev and get best of both worlds?  I guess I'm the kinda person who likes the less sharper cores and halos more like the filmy ones, rightly or wrongly.  I will try in siril to see what I achieve too.

Thanks
Lee

Edited April 19, 2022 by AstroNebulee

[Budgie1]

2 hours ago, AstroNebulee said:

Can I ask why you chose the L2 over the much suggested L3?

The main reason was that it was in the FLO sales at a much reduced price! Apart from that, the L2 is for general use with a corrector/reducer and the colour correction on my 80ED & 100ED isn't too bad.

Having processed your Rosette image, the L3 may be the better option for your setup.

I've done a process in PI and it's below. The focus is fine and there's good detail in there, I haven't removed too much of the background gradient because it would make it too black and remove some of the Ha nebulosity from the edges. The stars have been reduced, but not too much, and I removed the magenta from around them. There isn't that much noise in the image TBH, but it's easy to introduce it so sometimes less is more when processing.  

Anyway, here's what I got. I may have another go at it tonight as I'm not happy with the dark rings around the stars in the centre of the nebula and it's looking a bit washed out.

[AstroNebulee]

4 minutes ago, Budgie1 said:

The main reason was that it was in the FLO sales at a much reduced price! Apart from that, the L2 is for general use with a corrector/reducer and the colour correction on my 80ED & 100ED isn't too bad.

Having processed your Rosette image, the L3 may be the better option for your setup.

I've done a process in PI and it's below. The focus is fine and there's good detail in there, I haven't removed too much of the background gradient because it would make it too black and remove some of the Ha nebulosity from the edges. The stars have been reduced, but not too much, and I removed the magenta from around them. There isn't that much noise in the image TBH, but it's easy to introduce it so sometimes less is more when processing.  

Anyway, here's what I got. I may have another go at it tonight as I'm not happy with the dark rings around the stars in the centre of the nebula and it's looking a bit washed out.

Thats quite amazing.  There's a lot more detail there that I haven't managed to pull out  yet and looks more natural, especially the dark nebulosity 'tendrils' towards the centre of the nebula. 

You had a good deal on your L2 filter.  I think the L3 as you say will be the one I should have for my set up.

The autodev module in startools produces much the same halo effect as does in pixinsight which is the more natural way of the star, that's the part I have trouble with is the darker halo especially when against nebula.  I have to agree sometimes less is more and ill have to really hone that in to my processing, I hope I'm getting there slowly.  More perseverance on my part needed.  Can I ask did you see a lot of blue fringing around the brighter stars?
Cheers

Lee

[Budgie1]

3 hours ago, AstroNebulee said:

Can I ask did you see a lot of blue fringing around the brighter stars?

The workflow I use in PI is to do the background extraction and noise reduction before stretching. Then use StarNet or StarExterminator to separate the stars from the background, so I can work each of them separately. 

Once stretched, the larger stars had more of a magenta fringing to them. PI has a script for removing this, which gave them a bit of the blue fringe, so I lowered the amount of blue using curves. 

Once I was happy with the stars, I moved on to the nebula and played with various tools to get that to where I thought it looked good, before combining the stars & background together again.  

 

[AstroNebulee]

5 minutes ago, Budgie1 said:

The workflow I use in PI is to do the background extraction and noise reduction before stretching. Then use StarNet or StarExterminator to separate the stars from the background, so I can work each of them separately. 

Once stretched, the larger stars had more of a magenta fringing to them. PI has a script for removing this, which gave them a bit of the blue fringe, so I lowered the amount of blue using curves. 

Once I was happy with the stars, I moved on to the nebula and played with various tools to get that to where I thought it looked good, before combining the stars & background together again.  

 

That's some good advice from your workflow there and something I can hopefully work towards using the software I have available to me, thank you 👍

[Budgie1]

24 minutes ago, AstroNebulee said:

That's some good advice from your workflow there and something I can hopefully work towards using the software I have available to me, thank you 👍

No problem Lee, 

It doesn't matter which software you use for post-processing, they all take time to get used too so you know what they can do. When it's cloudy or I have some spare time in the evenings, I reprocess an older stack to see if I can make it better then the original. I also pick up hints & tips off videos and try them out. Some work, some don't but I can tune my workflow to include those that do. 

The best processing software is the one you're happy and confident using and the one which produces the best results for you.  

[ollypenrice]

If you have Photoshop you might consider buying what we old folks still call Noel's Actions, but which is now known as Pro-digital Astronomy Tools. This is a very, very good set of actions which includes two variants of a blue-violet bloat reducing routine. It does work, as do many of the other actions which are great time savers - eg a star selection tool.

You can also reduce bloated stars in Photoshop using this method:

Copy Layer.

Eraser, well feathered and a little larger than the bloat you want to reduce. Top layer active, take off the top layer with this eraser over the star and its bloat. You won't see anything happen because the bottom layer is still the same as the top.

Bottom layer active. Curves. Place the cursor as close to the outside of the bloat as possible and alt click to put a fixing point on the background just outside the bloat. Place another fixing point on the graph below that. Now pull down the Curve above the fixing point and shape it while looking at the now-reduced star of the bottom layer. Adjust colour balance and staturation to taste and flatten.

You wouldn't want to do dozens of stars like this but a few don't take long and several can be done together if they are sitting in a background of the same brightness as each other.

Olly

Edited April 19, 2022 by ollypenrice
typo

[AstroNebulee]

1 hour ago, Budgie1 said:

No problem Lee, 

It doesn't matter which software you use for post-processing, they all take time to get used too so you know what they can do. When it's cloudy or I have some spare time in the evenings, I reprocess an older stack to see if I can make it better then the original. I also pick up hints & tips off videos and try them out. Some work, some don't but I can tune my workflow to include those that do. 

The best processing software is the one you're happy and confident using and the one which produces the best results for you.  

Yep I'm still learning the various pieces of software out there, starting to find which ones I'm becoming comfortable with and learning new parts of them. As in my copy of an old photoshop it won't do somethings that are shown on videos or tutorials but gimp I can do the things I can't do properly. This is what I've been doing whilst off with covid, trying to reprocess old data that I was happy with before but seeing it now needs a reprocess. Thank you all taking your time out to help me in my baffoonary. 

1 hour ago, ollypenrice said:

If you have Photoshop you might consider buying what we old folks still call Noel's Actions, but which is now known as Pro-digital Astronomy Tools. This is a very, very good set of actions which includes two variants of a blue-violet bloat reducing routine. It does work, as do many of the other actions which are great time savers - eg a star selection tool.

I go have the astronomy tools set for photoshop and have used the small blue/purple halo killer a lot before just it leaves a rather grey halo to sort, also I use the deep space or space noise reduction. Very useful just for those two parts. 

I shall try the tip on reducing the star bloat thank you, won't be able to do it to all of them if needed but looks very good to treat the few that are really bloated as you say. 

With these much lighter evenings now I can get to grips with reprocessing ready for the cloudless nights at weekends and when darker earlier 😜

Thank you all 👍

Edited April 19, 2022 by AstroNebulee
Addition

[ollypenrice]

2 hours ago, AstroNebulee said:

Yep I'm still learning the various pieces of software out there, starting to find which ones I'm becoming comfortable with and learning new parts of them. As in my copy of an old photoshop it won't do somethings that are shown on videos or tutorials but gimp I can do the things I can't do properly. This is what I've been doing whilst off with covid, trying to reprocess old data that I was happy with before but seeing it now needs a reprocess. Thank you all taking your time out to help me in my baffoonary. 

I go have the astronomy tools set for photoshop and have used the small blue/purple halo killer a lot before just it leaves a rather grey halo to sort, also I use the deep space or space noise reduction. Very useful just for those two parts. 

I shall try the tip on reducing the star bloat thank you, won't be able to do it to all of them if needed but looks very good to treat the few that are really bloated as you say. 

With these much lighter evenings now I can get to grips with reprocessing ready for the cloudless nights at weekends and when darker earlier 😜

Thank you all 👍

The trick with any of the actions, or indeed any global processing alteration, is to use it as a layer and then select the opacity of the altered layer and/or use the selection tools to isolate which alterations to keep and which to erase. The Colour Select tool s very good for this.

Olly

[AstroNebulee]

53 minutes ago, ollypenrice said:

The trick with any of the actions, or indeed any global processing alteration, is to use it as a layer and then select the opacity of the altered layer and/or use the selection tools to isolate which alterations to keep and which to erase. The Colour Select tool s very good for this.

Olly

So am I correct in thinking, say I use the remove blue/purple halo action tool in a new layer (as I normally do) then I can reduce the opacity to actually bring some of the blue/purple fringing back in to try to offset some of the hard grey halo left behind? Excuse if I sound like a doofus. 

[900SL]

I have an L2 1.25" screws straight into my ZWO camera I use as standard.

The L3 has more cut off each end and is best for trying to deal with purple fringing CA, on my Askar 180 which, despite the makers claims and charts, isn't a well corrected triplet

[AstroNebulee]

36 minutes ago, 900SL said:

I have an L2 1.25" screws straight into my ZWO camera I use as standard.

The L3 has more cut off each end and is best for trying to deal with purple fringing CA, on my Askar 180 which, despite the makers claims and charts, isn't a well corrected triplet

Thank you, the L3 seems to be the one for my set up as suggested👍

Also so it doesn't matter that my 2 inch filter is where it is in my imaging train eg scope - rotator with filter screwed in - FF - extension tubes - 294mc pro combined with tilt adjuster? 

Edited April 19, 2022 by AstroNebulee
Add image

[Budgie1]

I've just noticed the field flattener you're using, is it a Stella Mira FF?

If it is,  I got one so I could use it with my Evostar 100ED DS Pro to allow me to use the full 900mm focal length and I never get good sharp images with it. I tried it once with my 80ED DS Pro and that was the same, so I now only use the SkyWatcher 0.85 RF/FF for each scope.

It may be worth trying an imaging session on a target you've previously imaged with the FF, only try it without the FF to see if there's any difference with the star bloating. You won't get the flat field but concentrate on the centre of the image and see if there's an improvement or not.