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Daystar Quark Chromo Wavelength usage when imaging

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#1 ilan_shapira

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Posted 22 November 2020 - 05:29 AM

I have been imaging the sun for the past month using a Quark Chromo with an Explore Scientific 102AR (F/6.5) & ZWO ASI178mm

 

So far so good, I managed to get pleasing images of sunspots and active regions. Still got work ahead of me but I am on the right path.

 

Any of you who are using the Quark for imaging, do you set the wavelength differently? In all tutorial videos I watched, no one ever talks about this specific setting.

I see that most are using the exposure and gain to control whether imaging chromosphere, prominences or both.

 

When taking images of pure Chromosphere, using 0.3A provides the most detailed images, but when trying to image an area that have the limb as well, the area close to the limb is getting blurry.

 

I did one experiment last week and turned the dial all the way to the other side and took an image of the sunspot AR2782 (I think). On screen it looked brighter - you can almost say whiter and I lost details so I kept it to be processed last.

When I did processed it, It came up better than I expected. Less details on the surface, but it looks more focused from surface to limb.

 

What is your preferred wavelength setting when imaging with the quark, do you ever change it?

Do you image both surface and proms in a single video?

I know that stopping down the aperture can get a better surface contrast, but before I do that (already have the mask ready), I really want to know and understand the mechanic better.

 

Example 1 - using 0.3A

gallery_299831_14858_2189352.jpg

 

Exmple 2 - using 0.5A

gallery_299831_14858_4801908.jpg

 

And the last, as it is not written on the quark itself, do any of you know exactly where the 0.3A and where is the 0.5A? smile.gif just to make sure I am not confusing stuff here:

gallery_299831_14856_311004.jpg

 

 

Thanks in advance.


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#2 spatzek

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Posted 22 November 2020 - 06:50 AM

Ian, the Chromo Quarks can be made from anywhere from 0.55A to 0.25. You dont have a guaranteed sub-A in a Quark. The temperature settings ONLY handles blue and red wings and central band not the etalon passband. 
You can only qualify how good a Quark filter really are visually. Its done by observers who knows how a 0.7A to 0.3A Sun look in a telescope. The same goes if we talk about spectral uniformity and finesse. I do test Quarks and I can do it because I have a Quantum 0.6A and a SolarSpectrum 0.3A filters. They are calibrated filters. 
The only way to get your Quark to work with wider passband is to get a faster telescope. 

 


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#3 ilan_shapira

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Posted 22 November 2020 - 08:18 AM

Thanks for the detailed answer,

I never had a chance to actually observe visually with this unit. I did observed few times using a fiend's Lunt dedicated telescope, more tuned for prominences as they were very nicely visible with less surface details, but I am not an expert on the subject.

So far, for imaging purposes, I greatly enjoy this unit and still learning this field. You added to the knowledge, thanks for that



#4 MalVeauX

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Posted 22 November 2020 - 09:25 AM

Heya,

 

Good images!

 

Every Quark is different, so there's no setting for everyone. However, you can map your Quark. First, start with a very long focal-ratio so that you can get the longest focal-ratio into that telecentric amplifier and then into the etalon. Something F10+ is a great way to go to get well into the F40+ area. Then focal-reduce after the Quark to get it to be reasonable again. Then, map the Quark by starting with your setting at 12 oclock. Let it reach temperature and show green light. Record an image of an area that should have high contrast, such as a filament or plage (don't use prominences). Then do the same thing at every setting going counter-clockwise (blue wing) and the same in every setting clockwise (red wing). Do it all on the same feature for each, again, target something that really shows high contrast when on band such as a plage or filament on the surface of the disc. Then go back and look for the setting in your images that has the darkest surface brightness and highest contrast on plage/filament. That should be the setting for your geographic location, temperature, pressure, etc. You can park it there indefinitely if you are always in the same location.

 

For example, here's all the settings on my previous Quark that clearly shows when it comes on band with HA (image 01 is fully clockwise, image 10 is fully counter-clockwise, so my Quark was on band when tuned as far into blue wing as possible).

 

post-256858-0-58411400-1570412207.gif

 

Very best,


Edited by MalVeauX, 22 November 2020 - 09:32 AM.

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#5 hopskipson

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Posted 22 November 2020 - 12:28 PM

Really nice images you captured Ilan.  I think your Quark is a keeper!  As Marty explains, you have to experiment and find where your best setting is located and then you can dial in different features as you please.


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#6 ilan_shapira

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Posted 22 November 2020 - 12:48 PM

Heya,

 

Good images!

 

Every Quark is different, so there's no setting for everyone. However, you can map your Quark. First, start with a very long focal-ratio so that you can get the longest focal-ratio into that telecentric amplifier and then into the etalon. Something F10+ is a great way to go to get well into the F40+ area. Then focal-reduce after the Quark to get it to be reasonable again. Then, map the Quark by starting with your setting at 12 oclock. Let it reach temperature and show green light. Record an image of an area that should have high contrast, such as a filament or plage (don't use prominences). Then do the same thing at every setting going counter-clockwise (blue wing) and the same in every setting clockwise (red wing). Do it all on the same feature for each, again, target something that really shows high contrast when on band such as a plage or filament on the surface of the disc. Then go back and look for the setting in your images that has the darkest surface brightness and highest contrast on plage/filament. That should be the setting for your geographic location, temperature, pressure, etc. You can park it there indefinitely if you are always in the same location.

 

For example, here's all the settings on my previous Quark that clearly shows when it comes on band with HA (image 01 is fully clockwise, image 10 is fully counter-clockwise, so my Quark was on band when tuned as far into blue wing as possible).

 

attachicon.gifpost-256858-0-58411400-1570412207.gif

 

Very best,

Many thanks for the detailed answer! I will use my time tomorrow testing it. Very helpful

 

Really nice images you captured Ilan.  I think your Quark is a keeper!  As Marty explains, you have to experiment and find where your best setting is located and then you can dial in different features as you please.

Thank you, I am happy with the results so far, will do the test Marty suggested, had to do it at some point to get even better


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#7 BYoesle

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Posted 22 November 2020 - 01:51 PM

Hi Ilan,

 

The first image is closest to being on band for most of the image, your second is significantly off band. Note the density of the filament and the brightness of the plage areas in the first image. These essentially disappear in your lower image, and the sunspot penumbra is enhanced and "spiky" mottles become visible off-band, especially on the left.

 

You have a significant contrast/bandpass gradient from left to right across the etalon. This is especially noticeable in your second image. But as others have noted, your etalon appears to be one of the better Quark performers.


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#8 briansalomon1

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Posted 23 November 2020 - 08:55 AM

Ian, the Chromo Quarks can be made from anywhere from 0.55A to 0.25. You dont have a guaranteed sub-A in a Quark. The temperature settings ONLY handles blue and red wings and central band not the etalon passband. 
You can only qualify how good a Quark filter really are visually. Its done by observers who knows how a 0.7A to 0.3A Sun look in a telescope. The same goes if we talk about spectral uniformity and finesse. I do test Quarks and I can do it because I have a Quantum 0.6A and a SolarSpectrum 0.3A filters. They are calibrated filters. 
The only way to get your Quark to work with wider passband is to get a faster telescope. 

To clarify, if I want my quark chromosphere model to show prominences better all I need to do is put it in a scope with a lower focal ratio?


Edited by briansalomon1, 23 November 2020 - 09:16 AM.


#9 vincentv

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Posted 23 November 2020 - 10:10 AM

 

That should be the setting for your geographic location, temperature, pressure, etc. You can park it there indefinitely if you are always in the same location.

Are you sure? If I understand correctly atmospheric variations affect air spaced etalons but not mica spaced.



#10 BYoesle

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Posted 23 November 2020 - 10:17 AM

 

To clarify, if I want my quark chromosphere model to show prominences better all I need to do is put it in a scope with a lower focal ratio?

 

Hi Brian,

 

Yes, that's correct. Review Etalon Basics with regard to the importance of acceptance angles:

 

FWHM-N.jpg

Faster f ratios increase the bandpass. Christian Viladrich

 

So if you use it at F8 you'll have a prominence filter only with a very bright disc full of continuum blocking visibility of chromospheric disc details. However, if the disc is too bright with this continuum it might actually make prominences more difficult to see, not easier.

 

I have also found depending on transparency that a wider bandpass seems reveal scattered continuum next to the Sun's disc as a rather obtrusive background glow that interferes with faint prominences. Double stacking can in these circumstances reduce the background glow of scattered continuum, and therefore presents a darker background against which prominences seem more crisp and have enhanced visibility, even though they are reduced in brightness overall due to the reduced transmission. This therefore seems to be a signal to noise issue / phenomena.


Edited by BYoesle, 23 November 2020 - 10:27 AM.

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