Eliminate reflection halos on Quarks?

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minhlead
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Eliminate reflection halos on Quarks?

Post by minhlead »

Hi there,
I am running into a problem that I think would benefit from collective wisdom so could anyone help me out on this?
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I am using my Quark to shoot FD via my 72mm scope reduced with a 2 inches reducer. The photo has some kind of ringed halo on the edge of the Sun. Sure I can drown those out by careful adjustment of the curve but still, I'd like to find a physical solution to this. I purposely leave some halo for the sake of this post.
Base on the look of this (the ringed appearance of the halo) I guess the reflection is coming off the inner thread inside extension tubes. My questions are:
1. Is this kind of reflection coming from before or after the Quark (or inside the Quark?)
2. If it's coming off of the threaded inside of the tube, what can I do to solve this? (I am thinking using some flat black paint to paint over the inner tubes and surfaces to reduce reflection, inside of the tubes already painted black but the paint is shiny. I think a flat black would work better) Anyone with a better idea is very welcome. Thanks! :bow2


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Re: Eliminate reflection halos on Quarks?

Post by eroel »

Minh:
It could be the 2X reducer that you use on the 72mm refractor, try it without it and see if you still get the halos on the outer circumference.
What I always do, is to paint with flat black paint the interior of my tubes and the adapters at the focusing side.
I do not own a Quark, so I do not know if it could be one component of it.
Hope to see what other member of the forum think about your problem.
Best regards,
Eric.


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Re: Eliminate reflection halos on Quarks?

Post by jacinto »

Hi, I have noticed the same problem with the ss60-ds, but since I do not have a tilt adapter, I improvised one with the filter wheel, and I thought it could be stray light that was entering the camera through a slot, I plan to do some tests to rule that out.

Jacinto


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Re: Eliminate reflection halos on Quarks?

Post by minhlead »

eroel wrote: Mon Nov 29, 2021 4:17 pm Minh:
It could be the 2X reducer that you use on the 72mm refractor, try it without it and see if you still get the halos on the outer circumference.
What I always do, is to paint with flat black paint the interior of my tubes and the adapters at the focusing side.
I do not own a Quark, so I do not know if it could be one component of it.
Hope to see what other member of the forum think about your problem.
Best regards,
Eric.
Thanks, eric. I painted the interior with black flat paint. Let see hơ it goes.


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Re: Eliminate reflection halos on Quarks?

Post by minhlead »

jacinto wrote: Mon Nov 29, 2021 5:34 pm Hi, I have noticed the same problem with the ss60-ds, but since I do not have a tilt adapter, I improvised one with the filter wheel, and I thought it could be stray light that was entering the camera through a slot, I plan to do some tests to rule that out.

Jacinto
I dont think it's the stray light though. Most likely reflections.


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Re: Eliminate reflection halos on Quarks?

Post by minhlead »

Okay so after some trial, I think I found the answer to this. I'll post it here as a reference for anyone need it in the future. I have tried the following:
1. Paint the interior of everything after the Quark to the camera with flat black paint. Result: Some improvement over total reflection but very slight, not noticeable at first sight but apparent when comparing shots from 2 sessions. In a word: it does help a bit but not what I am looking for.
2. Change the readmode of the camera from 8 bits to 16 bits (RAW8 and RAW16 on Sharpcap). The frame rate is now halved and the file size is doubled but the improvement is apparent. The ringed halo completely disappeared, it's not a gradual gradient instead that can easily be eliminate with curving and leave no trace of residual ringing.
Conclusion: The ringed halo likely due to lack of grey level in the shadow when using low bit rate read mode. The 16 bits read mode provide better gradient in shadow with less sampling error but coming with heafty cost in file size and frame rate. Using which is up to you.
Here is a final picture that I processed from a 16 bits raw video. The higher bitrate also make processing the proms a bit easier with more detail.
assss.jpg
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Re: Eliminate reflection halos on Quarks?

Post by Montana »

Mmm, is that the IMX174 chip? I have horrible banding with my ASI174 but I thought it was my 4K screen as it wasn't like this on my last computer. I have spent ages with colour chucks etc getting the colour correct to reduce it right down. I found that when viewing a prominence it showed it with only a few shades of grey and impossible to see fine detail.

However, I use 16bit ser anyway, maybe my problem is my monitor. I also get the banding in blacks and greys on any video playing, not just my camera. Have you checked your monitor too?

Alexandra


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Re: Eliminate reflection halos on Quarks?

Post by minhlead »

Montana wrote: Tue Nov 30, 2021 2:19 pm Mmm, is that the IMX174 chip? I have horrible banding with my ASI174 but I thought it was my 4K screen as it wasn't like this on my last computer. I have spent ages with colour chucks etc getting the colour correct to reduce it right down. I found that when viewing a prominence it showed it with only a few shades of grey and impossible to see fine detail.

However, I use 16bit ser anyway, maybe my problem is my monitor. I also get the banding in blacks and greys on any video playing, not just my camera. Have you checked your monitor too?

Alexandra
It is the IMX174 chip. I don't think it was the monitor since every screen I view this on has this problem. As soon as I turn on 16 bits, the banding go away right on the live view.


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Scope: SkyRover (Kunming Optics) 152mm F/6 Doublets
Mount: JTW Tridents GTR
Camera:
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Re: Eliminate reflection halos on Quarks?

Post by Rusted »

I never get banding from my ZWO 174MM using 8 bit in SharpCap + 27" AOC semi-UHD monitor. <sniff> :cry:


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Re: Eliminate reflection halos on Quarks?

Post by minhlead »

Montana wrote: Tue Nov 30, 2021 2:19 pm Mmm, is that the IMX174 chip? I have horrible banding with my ASI174 but I thought it was my 4K screen as it wasn't like this on my last computer. I have spent ages with colour chucks etc getting the colour correct to reduce it right down. I found that when viewing a prominence it showed it with only a few shades of grey and impossible to see fine detail.

However, I use 16bit ser anyway, maybe my problem is my monitor. I also get the banding in blacks and greys on any video playing, not just my camera. Have you checked your monitor too?

Alexandra
Oh and I forgot to mention this: If you are having problem with the proms having too few shades of grey (and the shadows too) then perhaps you should try increasing the gain of the camera when capturing. The increasing gain would introduce some random noise into the picture which helps increase bit depth (number shades of grey) of the final stacked photo. Base on my experience, the right ammount of noise in the shadows (especially in the proms) would do a lot in term of bringing more gradual transitions and details to the proms when you adjusting the curve of stacked image.
If you have the time, this is a very compelling read about the impact of stacking to bitdepth.
https://www.stark-labs.com/craig/resour ... acking.pdf


Minh.
Loves from Viet Nam <3
My gear:
Scope: SkyRover (Kunming Optics) 152mm F/6 Doublets
Mount: JTW Tridents GTR
Camera:
PlayerOne Apollo M-Max
Quark Chromosphere Doublestacked with PST etalon
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Re: Eliminate reflection halos on Quarks?

Post by jacinto »

minhlead wrote: Tue Nov 30, 2021 1:40 pm Okay so after some trial, I think I found the answer to this. I'll post it here as a reference for anyone need it in the future. I have tried the following:
1. Paint the interior of everything after the Quark to the camera with flat black paint. Result: Some improvement over total reflection but very slight, not noticeable at first sight but apparent when comparing shots from 2 sessions. In a word: it does help a bit but not what I am looking for.
2. Change the readmode of the camera from 8 bits to 16 bits (RAW8 and RAW16 on Sharpcap). The frame rate is now halved and the file size is doubled but the improvement is apparent. The ringed halo completely disappeared, it's not a gradual gradient instead that can easily be eliminate with curving and leave no trace of residual ringing.
Conclusion: The ringed halo likely due to lack of grey level in the shadow when using low bit rate read mode. The 16 bits read mode provide better gradient in shadow with less sampling error but coming with heafty cost in file size and frame rate. Using which is up to you.
Here is a final picture that I processed from a 16 bits raw video. The higher bitrate also make processing the proms a bit easier with more detail.
assss.jpg
Thanks for this information it is very valuable, I have the same problem, I am going to try with 16 bit mode


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