Tuning of Quark?

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Tuning of Quark?

Post by minhlead »

Hi everyone,
First time poster here. I've just got started in Solar imaging. I am from Viet Nam and I'm the first one here diving into solar Ha imaging so there's a lot to learn and no one to learn from (in VN).
I have a Quark and use 2 scope with it, a FRA400@F/7 and my trusty Sharpstar 107Ph @F/6.5. I am imaging with an OSC (QHY294C).
I have already taken some images with my Quark and so far I'm happy with it. But I have a few questions that I'd like to share, hoping you guys can shed some light on this.
1. According to the manual, the Quark shift blue when turn the knob counter clockwise. Also according to the manual, the CWL will shift blue if there are focuser droop, no matter which way the focuser droops, and DS said only if the focuser droop then I should turn the knob, otherwise, the knobs stays at 0. My Quark reaches the best contrast on the Filaments by turning the knob all the way counter clockwise (-5). So my question is, if the only source of CWL shifting is focuser droop and it only shift blue, shouldn't the knob be turned clockwise (red shift) to offset that? I'm really confused. And I can see this forum and anywhere else on the net, most of Quark owners also turn counter clockwise?
2. I know the common wisdom is just to get a mono but I am using a colour camera to do imaging. In my expericence, I can get my camera into bin 2x2 mode, in this way the sum of raw intensity value from all 4 pixels (RGGB) in CFA matrix is mapped into 1 pixel and the color information ignored, since the G and B all have the same response to Ha wavelength, I can get a color sensor bahaves like a mono with large pixel size. That way I lost 4 times the spatial resolution (a 12MPx OSC now becomes 3 MPx mono) but it's not really a problem anyway since the Quark already super oversampled (even at bin 2x2 I am still oversampled about 2 time). Maybe the cam would lost some QE due to CFA filtering but with ample of light from the Quark, it's a non problem, too. May be the only downside to this approach is frame rate, since the camera still have to readout all 4 pixels and that limit the frame rate (I get somewhere around 13-20 fps depending on my ROI). But since I got all the FOV of my M4/3, it's really great for full disk with rather long scope. I'm thinking about writing a debayer method for debayering the raw data instead of relying on the camera's SDK "mono binning". The debayer method would be based on superpixel but with accumulative intensity and throw out the chrominance information. it'd be nice if anyone who have better knowledge than my can shed some light on this approach? Am I missing something?
3. My QHY294C only support record video in 8 bit mode. 16bit mode reserves specifically for stills. I am just wondering if using 8 bits can give inferior to 16 bits. (I do get some banding on my prominences if I push the curve agresssively). A quick google search reveal 16 bit may give you some advantage when SNR is high. The author of the same paper also claimed the bit depth also increased with stacking (as long as there are sufficient noise in the image) and I do not really know if my does. Any thoughts?
14_46_04_lapl5_ap2051 - Copy-SharpenAI-sharpen.jpg
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Re: Tuning of Quark?

Post by Montana »

A very warm and sunny welcome Minh :hamster: and great photos :bow

Everyone should invest at least 2 hours on a sunny day and thoroughly test their Quark. Every single one is different and I can certainly say mine had no droop as it was all in fixed click lock fittings. You need to start at 5 anticlockwise and take an image of an active region or filament in exactly the same place each time. Turn to -4 and wait until the green light and image again. Do this for every single setting. DO NOT use flats. Then process all the images and line them up. You will see a darker area drift over the image and out again. The area when most contrast is on shot is the setting you should always use from now on. It might be 0 but the chances are it will not be. Mine was +4 or +5.

https://solarnutcase.livejournal.com/12257.html

I hope this helps for this question but I am sure others will help on the camera ones :)
Alexandra


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Re: Tuning of Quark?

Post by MAURITS »

Welcome Minh, as Alexandra pointed out I have used the same method.
It''s the only way to see the differences in the Quark clicks.


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Re: Tuning of Quark?

Post by ffellah »

Welcome Minh and happy solar imaging. Your images came out really well.

Franco


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Re: Tuning of Quark?

Post by minhlead »

Montana wrote: Wed May 05, 2021 9:15 am A very warm and sunny welcome Minh :hamster: and great photos :bow

Everyone should invest at least 2 hours on a sunny day and thoroughly test their Quark. Every single one is different and I can certainly say mine had no droop as it was all in fixed click lock fittings. You need to start at 5 anticlockwise and take an image of an active region or filament in exactly the same place each time. Turn to -4 and wait until the green light and image again. Do this for every single setting. DO NOT use flats. Then process all the images and line them up. You will see a darker area drift over the image and out again. The area when most contrast is on shot is the setting you should always use from now on. It might be 0 but the chances are it will not be. Mine was +4 or +5.

https://solarnutcase.livejournal.com/12257.html

I hope this helps for this question but I am sure others will help on the camera ones :)
Alexandra
Thanks Alexandra. Your article encouraged me to do a tuning testing of my Quark even before I bought one :D. Thanks for the great guide.
Could you please elaborate why shouldn't I use flats?
Last edited by minhlead on Wed May 05, 2021 12:13 pm, edited 1 time in total.


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Re: Tuning of Quark?

Post by minhlead »

MAURITS wrote: Wed May 05, 2021 9:25 am Welcome Minh, as Alexandra pointed out I have used the same method.
It''s the only way to see the differences in the Quark clicks.
Thanks Maurits, I was trying to eyeballing it and see it maybe somewhere -4, -5. Figure I would try Alexandra method as soon as I got the sun again.


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Re: Tuning of Quark?

Post by Montana »

Minh, if you use flats it will remove the dark band of 'on band' moving across the image and equalise the band. You need to see where this dark band is to know where centreline 'on band' is :) this will make it much more obvious which dial setting is the correct one.

Alexandra


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Re: Tuning of Quark?

Post by minhlead »

ffellah wrote: Wed May 05, 2021 10:14 am Welcome Minh and happy solar imaging. Your images came out really well.

Franco
Thanks Franco,
The first time I peeked out of the 32mm eyepiece with my Quark my heart skipped a few beats. Really an exciting experience. But the scorching tropical Sun prevents me from doing visual as usual as I'd like so it's imaging for now. Happy to share it with you guys.


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Re: Tuning of Quark?

Post by minhlead »

Montana wrote: Wed May 05, 2021 12:13 pm Minh, if you use flats it will remove the dark band of 'on band' moving across the image and equalise the band. You need to see where this dark band is to know where centreline 'on band' is :) this will make it much more obvious which dial setting is the correct one.

Alexandra
Thanks Alexandra. I reread your article and see what you are talking about. Missed that the first time. Now to think again, I do see a part of the frame (on 1 side of the sensor) where the contrast is very low and exposure is high (when I slew the filament to it, the filament just disappear no matter how I adjust the exposure. I was feared it is the much dreaded "sweet spot" people was referring to. But now after seeing your post I think it might be the on band drifting out of the frame. Maybe the dial setting I was using (-5) is not optimal. Let me try again. Strange isn't it? I think the Quark's etalon got heated to adjust the CWL, shouldn't it be very uniform when adjusting the bandpass? This looks like a tilting etalon?


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Re: Tuning of Quark?

Post by marktownley »

Welcome to the forum! Looks like you're getting some nice results from the setup even if the quark is at the end stop.


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Re: Tuning of Quark?

Post by Rusted »

Welcome to Solar Chat. Glad to see you made it over safely from SGL. :D

If we all started solar imaging from your high level of technical knowledge we'd all be experts. Even me! :lol:


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Re: Tuning of Quark?

Post by AbigailRoss »

Hello, the sun photos are just unbelievably beautiful, great job man


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Re: Tuning of Quark?

Post by eroel »

Minh:
A set of beautiful images with a color camera.
Well done and welcome to this incredible Forum where we all learn.
Eric.


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Re: Tuning of Quark?

Post by minhlead »

Thanks guys for the heartwarming welcomes. Appreciated it, and I must say I am amazed with the homey vibe of this community. For me, to have this Quark is a little adventure it self. Anyone follows my post over SGL or CN will know this.
But I am glad everything turned out okay, also glad that I decided to push on despite my unpleasant first impression with DS.
This noon I got about half an hour of clear sky and I tried Alexandra's test. I got from -5 to -2 and the view progressively worsen so I should I need to test any futher?
In the following photos -5 is on the left and minus -2 is on the right
Screenshot 2021-05-06 194315.png
Screenshot 2021-05-06 194315.png (462.07 KiB) Viewed 1054 times
Screenshot 2021-05-06 194058.png
Screenshot 2021-05-06 194058.png (962.54 KiB) Viewed 1054 times


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Re: Tuning of Quark?

Post by Montana »

Mmm that's a tough one. If I was just looking at the first I would say -3 or -2 looks best and would be interesting to see further on the scale. Looking at the bottom set, they all don't look that great ;) all look off band to me. Weird!
I would definitely do the whole scale.

Alexandra


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Re: Tuning of Quark?

Post by minhlead »

Montana wrote: Thu May 06, 2021 5:10 pm Mmm that's a tough one. If I was just looking at the first I would say -3 or -2 looks best and would be interesting to see further on the scale. Looking at the bottom set, they all don't look that great ;) all look off band to me. Weird!
I would definitely do the whole scale.

Alexandra
Thanks alexandra. I'll do the whole scale. Just hoping for better weather now!


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Re: Tuning of Quark?

Post by marktownley »

Are the pics above straight out of AS3? No sharpening / messing around with?


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Re: Tuning of Quark?

Post by Starry Jack »

Minh,
Amazing results particularly since you are using color. I might experiment again with color.

My setting is -5 always after doing many tests.

But, higher values also show different elements better I believe such as Ellen an bombs or proms or surface. By now I forget which is best on proms or surface but I am very happy overall with -5.

Jack


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Re: Tuning of Quark?

Post by minhlead »

marktownley wrote: Thu May 06, 2021 7:18 pm Are the pics above straight out of AS3? No sharpening / messing around with?
No. That's the same amount of stretching and deconvolution applied to them all. If I take the resukt straight from AS3 then jt's kinda blurry and hard to judge.


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Re: Tuning of Quark?

Post by minhlead »

Starry Jack wrote: Thu May 06, 2021 11:07 pm Minh,
Amazing results particularly since you are using color. I might experiment again with color.

My setting is -5 always after doing many tests.

But, higher values also show different elements better I believe such as Ellen an bombs or proms or surface. By now I forget which is best on proms or surface but I am very happy overall with -5.

Jack
Thanks, Jack. Looks like I am having the same as you do. Then it goes back to my question, if the only source of cwl shifting is focuser droop and it only shift blue then everyone must have their quark tuned clockwise right?


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Re: Tuning of Quark?

Post by marktownley »

minhlead wrote: Thu May 06, 2021 11:27 pm
marktownley wrote: Thu May 06, 2021 7:18 pm Are the pics above straight out of AS3? No sharpening / messing around with?
No. That's the same amount of stretching and deconvolution applied to them all. If I take the resukt straight from AS3 then jt's kinda blurry and hard to judge.
Unstretched and unconvoluted ones would be better...


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Re: Tuning of Quark?

Post by minhlead »

Starry Jack wrote: Thu May 06, 2021 11:07 pm Minh,
Amazing results particularly since you are using color. I might experiment again with color.

My setting is -5 always after doing many tests.

But, higher values also show different elements better I believe such as Ellen an bombs or proms or surface. By now I forget which is best on proms or surface but I am very happy overall with -5.

Jack
marktownley wrote: Fri May 07, 2021 5:13 am
minhlead wrote: Thu May 06, 2021 11:27 pm
marktownley wrote: Thu May 06, 2021 7:18 pm Are the pics above straight out of AS3? No sharpening / messing around with?
No. That's the same amount of stretching and deconvolution applied to them all. If I take the resukt straight from AS3 then jt's kinda blurry and hard to judge.
Unstretched and unconvoluted ones would be better...
Montana wrote: Thu May 06, 2021 5:10 pm Mmm that's a tough one. If I was just looking at the first I would say -3 or -2 looks best and would be interesting to see further on the scale. Looking at the bottom set, they all don't look that great ;) all look off band to me. Weird!
I would definitely do the whole scale.

Alexandra
Okay so I think I pinned down my problem with tuning. It seems my ambient temperature is too high (40*C for now and can be as high as 50*C in mid Summer), it pushes the CWL to the Red wing.
That is why despite all the focuser droop/tilting that I may have inside of my optical train, the cwl still shift red far enough that I have to put the knob at -5 (which is hard to reach since the ambient temperature is too high) and with knob is now at -5, I cannot shift blue any further and I feel I need like -6 or -7 to reach the highest possible contrast.
So now I think maybe if I introduce some more tilting to the optical train, I can have the CWL shift further to the blue wing and be more on band. Maybe it won't improve contrast, maybe it will, I think I wanna try to find out insfead of having stuck at -5 and wonder what I am missing.
I intend to introduce a controlled tilt with a field tilter (pictured)
20210515_161843.jpg
20210515_161843.jpg (253.88 KiB) Viewed 937 times
But I wanna ask how much tilting should it be?
I find a paper of Daystar about the Quantum PE (pictured bellow)
Screenshot_20210515-170613_OneDrive.jpg
Screenshot_20210515-170613_OneDrive.jpg (421.92 KiB) Viewed 937 times
that states the CWL shift of 1 A for 1 degree shift but the chart is scaled really big (on the scale of 5 A when I only need a tilt that'll shift the CWL about 0.2-0.3 A). So anyone know a formula to calculate the cwl shift with angle of incident ?


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Re: Tuning of Quark?

Post by minhlead »

Okay, a quick search on Google reveal this gems. http://www.astrosurf.com/viladrich/astr ... lar/FP.htm
It seems a tilt of 0.2-0.3 deg would shift the CWL about 0.15 A toward blue and keep the FWHM widening at a reasonable level. Lets put this to the test.


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Re: Tuning of Quark?

Post by minhlead »

Okay it seems we have author of the amazing paper in my previous post here in solar chat, Mr. christan viladrich
If it's not much of a problem, please give me your opinions here @christan viladrich
1. Should I introduce a tilt in front of the Quark to solve my problems? ( too hot ambient that makes tuning in coldest oven temperature (-5) hard to reach I hope tilting the etalon would blueshift the cwl and rise the onband temperature a few knobs, making reaching them in hot ambient easier. Also, the ambient temps too high shift CWL red too much that even with the oven at -5 I still feel like I am not entirely on-band so by tilting the etalon, I am hoping I can bring the on-band temperature to knob -2 or -3 allowing for some margin of tuning.
As your paper stated, tilting a mica spaced F-P etalon in telecentric light cone (which is what the Quark is, mine is with the original 4.2x barlow) not only shift the CWL but also widens the FWHM. And the widening effect is quite substantial (0.35A at just 0.5 deg tilting @F/30 according to your graph) so my Quark if it has 0.5A FWHM then will widen to 0.85A with just 0.5 deg tilt, which would surely kill the contrast.
So should I tilt, would it fixes my problems, and how much should I tilt?
2. A bit off topic.
Daystar stated on their website that
Each Quark is warranted to have a FWHM bandpass (when introduced into a focal plane beam of ~F7-F/9) of 0.25 - 0.5.
Combo Quark filters are warranted to have a FWHM bandpass (when introduced into a focal plane beam of >F/25) of 0.25 - 0.5.
http://www.daystarfilters.com/Quark/Qua ... mity.shtml
And Jen at DS assured me that after F/30 there're little to gain in FWHM. But as your graph shows a 0.3A etalon will only be 0.3 when F/D approaching 50. At 30, it behaves like a 0.5A etalon.
So the question is: what is more likely to be the fact here?
A. DS overstated their specs, all FWHM is measured with collimated beam and at recommended F ratio (F/30) it will widen.
B. Every Quark Chromosphere etalon (which stated to have FWHM less than 0.5A) is actually under 0.3A in collimated beam. (Which I find very hard to believe).
And according to your article then there are performance to be gained if I further stop down my system beyond F/30 right?
Thank you again for your article. And hope to hear from you.
P/s: anyone knows how to tag user in here?


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Re: Tuning of Quark?

Post by marktownley »

minhlead wrote: Sun May 16, 2021 7:56 am
So the question is: what is more likely to be the fact here?
What Christian has on his website is fact.


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Re: Tuning of Quark?

Post by christian viladrich »

Hello Minh,
It's nice to have you on board. I am sure you will have great views of the Sun from Vietnam. And this will complete the longitude coverage of the Sun by Solar Chat observers :-)
Here are some elements regarding your questions.

1) Regarding tilt in front of the Quark :

If the tilt is between the etalon and the telecentric, you will correct the issue with the center wavelength, but you will increase the FWHM depending on the amount of tilt. In this figure X is the tilt angle :
http://astrosurf.com/viladrich/astro/in ... -angle.JPG

if the tilt is in front of the telecentric, then there is no increase of the FWHM (good news), but no change of the CWL (bad news). So it does not change the issue you are facing.

Before the Quark came the Ion. Depending on the ambient temperature, the Ion could also have some issue reaching reference temperature. The cooling system (Peltier + fans) was a bit undersized.
Years ago, I used a big CCD camera for solar imaging. The camera was cooled by water circulation. It was very effective.
I don't know if you can try something like this with the Quark ? Or try convincing DayStar to make more powerfull cooling system ?


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Re: Tuning of Quark?

Post by christian viladrich »

2) Regarding FWHM as a function of f-ratio:
Optics are optics. There is no magic in it. The references are provided on my website:
http://astrosurf.com/viladrich/astro/in ... P-math.htm

Here is a comparison between images taken at f/27 and f/35 and a 0.3 A etalon :

http://astrosurf.com/viladrich/astro/so ... 03A-C8.jpg

http://astrosurf.com/viladrich/astro/so ... C8-F35.jpg

Indeed, quality of an etalon is not only about FWHM but also about uniformity of FWHM and CWL accross the etalon. For example, a FWHM of 0.3 A is meaning less if you have a drift of CWL of 0.6A accros the field.

Air-spaced etalon can now be tested by willing amateurs. See the related various posts on Solar Chat and also :
http://astrosurf.com/viladrich/astro/in ... sting.html

Testing of mica-spaced etalon is in the pipeline ;-) I hope to have some results during summer. Meanwhile, here is a very interesting paper including results here :
https://www.researchgate.net/publicatio ... XAMINATION


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Re: Tuning of Quark?

Post by christian viladrich »

3) Regarding 8-bit versus 16-bits.
For "usual" solar imaging, I never have found any difference. The only difference I have found is for solar eclipses or high dynamic range object like this:
http://astrosurf.com/viladrich/astro/te ... ndree.html

Still, I recently came onto something very much unexpected with the ASI 1600. In 8-bit acquisition, there is big difference in dynamic and S/N between the "fast" and "slow" modes of acquisition. This is as if the dynamic range is cut down in the "fast" mode. Indeed, the exposure time leading to image saturation is longer in the "slow" mode. The ASI 290 does not behave like this, nor the Basler 1920-155.


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Re: Tuning of Quark?

Post by christian viladrich »

4) Regarding BW versus color senor:
This is true you can use binning during acquisition. For full disk imaging, there is no issue. For high-resolution imaging, you could face a lack of light (since only one out of four pixels actually see Ha). Still, there is plenty you can do with your camera.


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Re: Tuning of Quark?

Post by minhlead »

marktownley wrote: Sun May 16, 2021 9:03 am
minhlead wrote: Sun May 16, 2021 7:56 am
So the question is: what is more likely to be the fact here?
What Christian has on his website is fact.
I know, i am operating on the assumption that his calculation are correct. What I am asking was "Is DS over stated their specs or their filter is actually have way lower bandpass that we can benefit from by stopping down futher than f/30?"


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Re: Tuning of Quark?

Post by minhlead »

christian viladrich wrote: Sun May 16, 2021 12:11 pm Hello Minh,
It's nice to have you on board. I am sure you will have great views of the Sun from Vietnam. And this will complete the longitude coverage of the Sun by Solar Chat observers :-)
Here are some elements regarding your questions.

1) Regarding tilt in front of the Quark :

If the tilt is between the etalon and the telecentric, you will correct the issue with the center wavelength, but you will increase the FWHM depending on the amount of tilt. In this figure X is the tilt angle :
http://astrosurf.com/viladrich/astro/in ... -angle.JPG

if the tilt is in front of the telecentric, then there is no increase of the FWHM (good news), but no change of the CWL (bad news). So it does not change the issue you are facing.

Before the Quark came the Ion. Depending on the ambient temperature, the Ion could also have some issue reaching reference temperature. The cooling system (Peltier + fans) was a bit undersized.
Years ago, I used a big CCD camera for solar imaging. The camera was cooled by water circulation. It was very effective.
I don't know if you can try something like this with the Quark ? Or try convincing DayStar to make more powerfull cooling system ?
Cannot seems to thank you enough for your answers, Christian. Exactly what I was looking for.
Just a quick question.
You said if the tilt is introduce in front of the telecentric barlow then there is no gain/loss in CWL or FWHM. But Daystar mentioned about focuser droop affects the CWL and the Quark must be temperature tuned to compensate for the CWL shift which suggests that a tilt in front of the telecentric (tilt of the whole Quark unit) will shift the CWL blue regardless of the direction of the tilt.
This is what confuses me. Could you please elaborate further? Also, my Quark is the newer model with unremovable barlow so i do not have the option of introducing the tilt between the telecentric barlow and the etalon.
Again, thanks


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Re: Tuning of Quark?

Post by minhlead »

christian viladrich wrote: Sun May 16, 2021 12:44 pm 4) Regarding BW versus color senor:
This is true you can use binning during acquisition. For full disk imaging, there is no issue. For high-resolution imaging, you could face a lack of light (since only one out of four pixels actually see Ha). Still, there is plenty you can do with your camera.
Actually in most OSC binning there are a mono mode where the intensity of the binned pixel is determined from the total intensity of all 4 pixels in the cfa then quadruped so the intensity of the binned pixel is almost 4x the brightess pixels. There are some loss due to transmission of the CFA but I find it works quite well overal, never ran into lack of light (I shot most of my images at 3ms at unity gain which is slower than many mono camera but useable I think.)


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Re: Tuning of Quark?

Post by minhlead »

christian viladrich wrote: Sun May 16, 2021 12:29 pm 2) Regarding FWHM as a function of f-ratio:
Optics are optics. There is no magic in it. The references are provided on my website:
http://astrosurf.com/viladrich/astro/in ... P-math.htm

Here is a comparison between images taken at f/27 and f/35 and a 0.3 A etalon :

http://astrosurf.com/viladrich/astro/so ... 03A-C8.jpg

http://astrosurf.com/viladrich/astro/so ... C8-F35.jpg

Indeed, quality of an etalon is not only about FWHM but also about uniformity of FWHM and CWL accross the etalon. For example, a FWHM of 0.3 A is meaning less if you have a drift of CWL of 0.6A accros the field.

Air-spaced etalon can now be tested by willing amateurs. See the related various posts on Solar Chat and also :
http://astrosurf.com/viladrich/astro/in ... sting.html

Testing of mica-spaced etalon is in the pipeline ;-) I hope to have some results during summer. Meanwhile, here is a very interesting paper including results here :
https://www.researchgate.net/publicatio ... XAMINATION
May I suggest a simpler setup to test the uniformity of the Quark:
I posted it in Stargazerlpunge but have no response there.
https://stargazerslounge.com/topic/3737 ... nt-4060882
In short, just get a small white LED (my phone's flash light works fine) , put it in front of the scope with the Quark and camera in place , shinning down the OTA and take an exposure (I took mine at 60s) . All the deformity/mica sheet cleave error/ dust spot will shows in the resulting photo.
Here is mine. The result looks bad with plenty of dust spots /mica cleaving scratches. But mine performs okay under the sun (not very uniform but flats does help.
Screenshot_20210314-133820_TeamViewer~2.jpg
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Re: Tuning of Quark?

Post by christian viladrich »

Hello Minh,
Regarding your test, it is not sensitive to change in CWL since your source of light is "broad band". In other words, if there is no change of FWHM, but only a change of CWL you will have an uniform image (if there is no local change in peak transmission of course).
On top of that, if your camera is not focused on the etalon surface, you won't be able to see the etalon small size effects (inclusions, cleavage defaults, etc).
You can improve on this by using an Ha lamp and a collimated beam, and using a camera focused on the etalon surface:
http://astrosurf.com/viladrich/astro/in ... 94-410.jpg
Still, this type of test is difficult to interpret in terms of CWL and FWHM uniformity.


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Re: Tuning of Quark?

Post by christian viladrich »

minhlead wrote: Sun May 16, 2021 3:21 pm
You said if the tilt is introduce in front of the telecentric barlow then there is no gain/loss in CWL or FWHM. But Daystar mentioned about focuser droop affects the CWL
Can you give me a link to the web page they say so ?


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Re: Tuning of Quark?

Post by minhlead »

christian viladrich wrote: Sun May 16, 2021 4:30 pm
minhlead wrote: Sun May 16, 2021 3:21 pm
You said if the tilt is introduce in front of the telecentric barlow then there is no gain/loss in CWL or FWHM. But Daystar mentioned about focuser droop affects the CWL
Can you give me a link to the web page they say so ?
http://www.daystarfilters.com/downloads/QuarkManual.pdf
It's in the page 3 of the Quark' s Manual
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Re: Tuning of Quark?

Post by minhlead »

christian viladrich wrote: Sun May 16, 2021 4:30 pm
minhlead wrote: Sun May 16, 2021 3:21 pm
You said if the tilt is introduce in front of the telecentric barlow then there is no gain/loss in CWL or FWHM. But Daystar mentioned about focuser droop affects the CWL
Can you give me a link to the web page they say so ?
So I've completed a tec cooler for the Quark, hoping to bring it down a few degrees below 30 and see if the CWL shift blue. Only if the clouds just go away


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Re: Tuning of Quark?

Post by minhlead »

christian viladrich wrote: Sun May 16, 2021 4:30 pm
minhlead wrote: Sun May 16, 2021 3:21 pm
You said if the tilt is introduce in front of the telecentric barlow then there is no gain/loss in CWL or FWHM. But Daystar mentioned about focuser droop affects the CWL
Can you give me a link to the web page they say so ?
Okay so I found a video of Jen at DS expalining the tuning process in more detail including what happens if you tilt the etalon.
https://youtu.be/L_tq1KA_QEA
(The part regading tilting is at 45:00 and 52:00)
And judging by the look of the spectrometer on the video, it seems tilting the etalon does not affect the FWHM much, the peak still seems pretty much as narrows after tilting to me.


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Re: Tuning of Quark?

Post by christian viladrich »

minhlead wrote: Wed May 19, 2021 5:27 am And judging by the look of the spectrometer on the video, it seems tilting the etalon does not affect the FWHM much, the peak still seems pretty much as narrows after tilting to me.
I give you a hint Minh ;-)
You can see several "teeth" of transmission on the screen. So it is only the etalon which is measured there, and not the whole unit (telecentric, ITF, BF, etalon).


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Re: Tuning of Quark?

Post by minhlead »

christian viladrich wrote: Thu May 20, 2021 6:10 pm
minhlead wrote: Wed May 19, 2021 5:27 am And judging by the look of the spectrometer on the video, it seems tilting the etalon does not affect the FWHM much, the peak still seems pretty much as narrows after tilting to me.
I give you a hint Minh ;-)
You can see several "teeth" of transmission on the screen. So it is only the etalon which is measured there, and not the whole unit (telecentric, ITF, BF, etalon).
I do aware of that. But the way Jen put it seems to suggest if the whole Quark (including the barlow and the etalon) tilts then the cwl will shift blue, just like when you tilt the etalon alone (minus the other "teeth" since they filtered out by the trimming filter).


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Re: Tuning of Quark?

Post by minhlead »

Montana wrote: Thu May 06, 2021 5:10 pm Mmm that's a tough one. If I was just looking at the first I would say -3 or -2 looks best and would be interesting to see further on the scale. Looking at the bottom set, they all don't look that great ;) all look off band to me. Weird!
I would definitely do the whole scale.

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christian viladrich wrote: Thu May 20, 2021 6:10 pm
minhlead wrote: Wed May 19, 2021 5:27 am And judging by the look of the spectrometer on the video, it seems tilting the etalon does not affect the FWHM much, the peak still seems pretty much as narrows after tilting to me.
I give you a hint Minh ;-)
You can see several "teeth" of transmission on the screen. So it is only the etalon which is measured there, and not the whole unit (telecentric, ITF, BF, etalon).
Alright,so tilting the whole Quark definitely shift the CWL.
I tilt the Quark and everything behind it with a field tilter about 1 degree and now the best setting no longer -5 but jump a few knobs to -3 or -2. (The 0 or -1 setting now have the best field uniformity but the local contrast is best with -3 or -2 setting.)
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Re: Tuning of Quark?

Post by marktownley »

You're doing some great experimentation here Minh, and getting some effective results.


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Re: Tuning of Quark?

Post by minhlead »

marktownley wrote: Sat May 22, 2021 9:55 am You're doing some great experimentation here Minh, and getting some effective results.
Thanks mark.


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Re: Tuning of Quark?

Post by rsfoto »

Hi,

The best result for me judging from my limited experience is -3


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Re: Tuning of Quark?

Post by minhlead »

rsfoto wrote: Sat May 22, 2021 3:50 pm Hi,

The best result for me judging from my limited experience is -3
same here :)) Completely newbie.


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Re: Tuning of Quark?

Post by Valery »

If the bottom images represent the full FOV, then the best new position is -5 or -4 and you just need to use a ROI (region of interest) and use this upper half of the field of view.
In general, uniformity wise this Quark is quite poor. It has a narrow enough bandwidth, but a huge gradiend of the central wave length position (poor CWL uniformity). If the size of this maximal ROI is OK for you, then use this Quark. If you want to use at least 80-90% of the FOV, then you should try to find a better Quark sample.

Sorry to tell you this fact (as this seen from your images), but better to know the truth.


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Re: Tuning of Quark?

Post by Valery »

Here you can see your screen shot at -5 with ROI indicated, then this ROI as a crop and the ROI image corrected for a field brightness non-uniformity.

At least you can move ahead. If you will use less reduction after the Quark and prior to the camera, the ROI will be larger on the camera chip.

Hope this helps.


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Re: Tuning of Quark?

Post by minhlead »

Valery wrote: Sat May 22, 2021 7:21 pm Here you can see your screen shot at -5 with ROI indicated, then this ROI as a crop and the ROI image corrected for a field brightness non-uniformity.

At least you can move ahead. If you will use less reduction after the Quark and prior to the camera, the ROI will be larger on the camera chip.

Hope this helps.


Valery
Excellent explaination, Valery. I do understand that my Quark have poor field uniformity, that's no secret the first time I look through the eyepiece, the "sweet band" effect is apparent on large fov. Unfortunately I am from VN and returning the Quark for a better one simply out of the question so I have to find a way to make it work with what I get. Luckily I am mostly an imaging guy and spend very little time doing visual so there are some trick that can be done.
I am using ROI to crop out the out of band exactly like your illustration, it's help speed up the frame rate a lot too (I am using a color camera at bin 2x2 so a full chip readout only gave me 16 or so fps, after cropping it's 30fps which is somewhat acceptable) and since the sensor is relatively large (M4/3) the FOV after cropping still about 30% larger than if I am using a mono camera with a 1/1,2 inches sensor like the IMX174 which I think is acceptable. And I've done some good images with this Quark so I think I'll keep it.
To my layman's eyes I find the -4 -5 setting seems to lack some local contrast in comparing with the -3, -2 settings, the filaments seems to be fainter in -4, -5 and surface features also less pronounced in -5. I am using -3 with cropping and flat calibration and some post processing trick to improve the field uniformity and the result is okay so far. But I'll surely try -5 per your advices. Thanks you for your time and helpful advices, Valery.
Last edited by minhlead on Sun May 23, 2021 3:44 am, edited 1 time in total.


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Re: Tuning of Quark?

Post by DeepSolar64 »

Hello Minh,
It's nice to have you on board. I am sure you will have great views of the Sun from Vietnam. And this will complete the longitude coverage of the Sun by Solar Chat observers :-) _ Christian Viladritch

We now have better solar coverage than the GONG network and lately have been more reliable! :band

James


Lunt 8x32 SUNoculars
Orion 70mm Solar Telescope
Celestron AstroMaster Alt/Az Mount
Meade Coronado SolarMax II 60 DS
Meade Coronado SolarMax II 90 DS
Meade Coronado AZS Alt/Az Mount
Astro-Tech AT72EDII with Altair solar wedge
Celestron NexStar 102GT with Altair solar wedge
Losmandy AZ8 Alt/Az Mount
Sky-Watcher AZGTI Alt-Az GoTo mount
Cameras: ZWO ASI178MM, PGR Grasshopper, PGR Flea
Lunt, Coronado, TeleVue, Orion and Meade eyepieces

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Montana
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Re: Tuning of Quark?

Post by Montana »

My pick would be -4, but -3 is OK :)

Alexandra


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