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Curiousity for imaging with Combo Quark @ 16"

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#1 carolinaskies

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Posted 10 September 2019 - 05:43 PM

OK, so I've got a Combo Quark coming this week to use with my refractors 80-152mm sizes.  I've got a 90MM ETX, 8" F/6.3 SCT and a big 16" LX200 w/full glass white light fitler. 

Now I understand a white light filter cuts all wavelengths down to .001 or whatever.   When I observed the total eclipse 2 years ago in that full aperture I could see granularity I never saw in my smaller 8" scope when I had a glass filter for it.  I'm guessing of course because aperture gives resolution even if you're cutting light down. I could see coronal activity during full eclipse as well.  It blew me away!  

My curiousity of "what if" has me thinking of trying the combo quark on the 16" with the white light glass filter.  It's not an ERF in the same sense as buying any full aperture ERF (huge money for that 16") of course because it is limiting all wavelengths not rejecting all but the H-Alpha.  But if I am imaging, not visual, wouldn't the quark essentially still be receiving the H-Alpha and the interanl 25mm blocking filter the Combo has on it doing the rejection?  Visually it might be quite dim, but with a camera set to longer exposure wouldn't it be utilizing full resolution of the 16?   

Am I crazy? Would it just result in simply not enough energy for the Quark to record?  

I know I can't be the first who has suggested and/or attempted such a ridiculous idea. 

Anyone with REAL experience doing this with actual imaging results?   

Given the reduction in light I don't think there's any danger to the Quark is there?  At worst it won't be sensitive enough is my thought. 


 



#2 hopskipson

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Posted 10 September 2019 - 05:51 PM

I have a feeling the amount of light that would get to the Quark would not be enough to get any image.



#3 BabyPepper

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Posted 10 September 2019 - 07:04 PM

zero image what so ever, you will see nothing.    You are going to need a $7000.00 full aperture erf on that scope, it is the only way to ever use a mirror based telescope with h-alpha. 

 

period.  

 

Refractors are king of h-alpha in terms of cost.   

 

Mirror based systems are only superior when you have that special, disposable income.  After spending that money ,  it will be like looking at ripples on a pond, waves of atmospheric turbulance due to horrible seeing conditions.

 

For literally one second out of every 5 minutes of viewing you will get a glimpse of something amazing however,    and for some people that 1 second is worth the investment.

 

I will post an animated image for you that highlights the atmospheric turbulence, nobody else does this because it is ugly as heck and not "good for business".  People go through great efforts to hide it in fact.


Edited by BabyPepper, 10 September 2019 - 07:11 PM.


#4 BabyPepper

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Posted 10 September 2019 - 10:29 PM

okay;  now i have a high speed camera that  records 750 frames in 1 second.. This capture represents just 8 milliseconds of atmospheric turbulence with a 160mm objective.      This is considered "great seeing".  

 

48714508468_20a449bf73_o.gif

 

 

Now factor in real time, and it turns to a puddle.  This is the honest truth about solar imaging with a large aperture, anybody that says otherwise is a liar.

 

48714527738_d6f434884e_o.gif



#5 BYoesle

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Posted 10 September 2019 - 10:42 PM

 

But if I am imaging, not visual, wouldn't the quark essentially still be receiving the H-Alpha and the interanl 25mm blocking filter the Combo has on it doing the rejection?

Unfortunately, a "white light" (e.g. photospheric continuum) filter does not selectively let through the H alpha emission feature of the chromosphere. Indeed, it reduces this emission feature - usually only visible during a total solar eclipse - by the same 100,000 times as any other wavelength. Lots have tried and failed, due to not understanding the fundamental nature of the absorption features being from the photosphere and the emission features visible from the chromosphere.

 

In the instance of using the Quark, it would be no different than using a nighttime H alpha filter. See: Using a night-time Ha filter for solar viewing: Part Two in The Best of Solar Threads.


Edited by BYoesle, 10 September 2019 - 11:05 PM.

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#6 carolinaskies

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Posted 11 September 2019 - 02:02 AM

I understand the explanation, but you don't state whether you actually tried this. A Quark is not a nighttime filter. Bandpass of the combo quark is .25-.5 btw

#7 BYoesle

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Posted 11 September 2019 - 04:30 AM

Hi Paul, 

 

No, I have not tried this.

 

Since you have the Quark Combo on the way, and a 16 inch glass white light filter (glass!) - you can give it a try waytogo.gif  

 

Visually it might be quite dim, but with a camera set to longer exposure wouldn't it be utilizing full resolution of the 16? ... Bandpass of the combo quark is .25-.5 btw

 

I wouldn't necessarily trust that particular FWHM specification, and even if it is accurate, the bandpass of the Combo will not be anywhere near 0.25 - 0.5 A at the f10 focal ratio of the 16 inch SCT, it will be much closer to a nighttime H alpha filter. Don't forget the Combo doesn't have a built in telecentric (4.2x) like the regular Quarks. You'll need at least a 3x Baader telecentric lens (f30) or 4X (f40 - better) to get anywhere near that FWHM.

 

So let's try a thought experiment: You go to a total solar eclipse, where your white light filter is used for the partial phases of the eclipse, reducing the brightness of the photosphere ~ 100,000 times. For totality, you take the filter off to see prominences around the limb of the Moon. Trying the camera route, to get the best resolution you set your ISO for 100, and at f30 (telecentric in place) of your 16 inch SCT prominences require an exposure of around 1/15 of a second. Reinstalling the OD5 white light filter you will see - nothing, nada, zip. Your camera exposure now becomes ~ 6,666 seconds (111 minutes - 1.85 hours) - obviously not practical for a total solar eclipse that usually lasts no more than a few minutes wink.gif

 

However, don't forget the H alpha emission (656 nm) is not the only prominence emission wavelength, you have the H beta (486 nm) for an eclipse, which will be removed by the H alpha filter, increasing the exposure even more for the white light filter use.

 

For hi-resolution images you not only have to deal with the atmosphere as noted by BabyPepper - you now have to deal with the highly magnified movement of the features themselves, which will be considerable over the necessary exposure. This defeats the goal of using the full resolution of the 16.

 

So again while I have not tried this, I look forward to seeing the results of anyone who makes the effort to try.



#8 carolinaskies

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Posted 11 September 2019 - 07:03 AM

I'll definitely give it a try because I think it would be quite an interesting experiment.

By the way I was reading in another thread that somebody was using a heat blocking filter available through Edmonds scientific

#9 MalVeauX

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Posted 11 September 2019 - 07:04 AM

Heya,

 

I don't have a 16", but the focal-ratio is the same and that's all that will really matter for the purpose of figuring out what will be on the other side to a sensitive camera sensor.

 

I of course tried it. If you have it, why not? Here's ND3.8 photo grade solar film on a 250mm F10.

 

28478575498_255e0210fa_c.jpg

 

The Quark side was black, no matter what.

 

There's no enough transmission. Lots of people have tried this. Your ERF has to have 90%+ transmission to begin with, and a Quark isn't a high transmission filter either, as it was built to be safe for visual. So as lots of people have tried, getting a cheap ERF by using solar film or solar glass (worse than film) on a big scope and a Quark, the result is a pretty black picture.

 

Ultimately it doesn't matter. The seeing will not support these apertures unless you're in an ideal location, early morning, and/or using a SSM and get lucky.

 

Very best,


Edited by MalVeauX, 11 September 2019 - 07:05 AM.

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#10 Spikey131

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Posted 11 September 2019 - 07:11 AM

What you need is a satellite.
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#11 carolinaskies

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Posted 11 September 2019 - 01:18 PM

Heya,

 

I don't have a 16", but the focal-ratio is the same and that's all that will really matter for the purpose of figuring out what will be on the other side to a sensitive camera sensor.

 

I of course tried it. If you have it, why not? Here's ND3.8 photo grade solar film on a 250mm F10.

 

28478575498_255e0210fa_c.jpg

 

The Quark side was black, no matter what.

 

There's no enough transmission. Lots of people have tried this. Your ERF has to have 90%+ transmission to begin with, and a Quark isn't a high transmission filter either, as it was built to be safe for visual. So as lots of people have tried, getting a cheap ERF by using solar film or solar glass (worse than film) on a big scope and a Quark, the result is a pretty black picture.

 

Ultimately it doesn't matter. The seeing will not support these apertures unless you're in an ideal location, early morning, and/or using a SSM and get lucky.

 

Very best,

Thanks for your personal experience... of course I'll prove it to myself with the 16" too... :)  


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#12 carolinaskies

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Posted 11 September 2019 - 01:54 PM

Hi Paul, 

 

No, I have not tried this.

 

Since you have the Quark Combo on the way, and a 16 inch glass white light filter (glass!) - you can give it a try waytogo.gif  

 

 

I wouldn't necessarily trust that particular FWHM specification, and even if it is accurate, the bandpass of the Combo will not be anywhere near 0.25 - 0.5 A at the f10 focal ratio of the 16 inch SCT, it will be much closer to a nighttime H alpha filter. Don't forget the Combo doesn't have a built in telecentric (4.2x) like the regular Quarks. You'll need at least a 3x Baader telecentric lens (f30) or 4X (f40 - better) to get anywhere near that FWHM.

 

So let's try a thought experiment: You go to a total solar eclipse, where your white light filter is used for the partial phases of the eclipse, reducing the brightness of the photosphere ~ 100,000 times. For totality, you take the filter off to see prominences around the limb of the Moon. Trying the camera route, to get the best resolution you set your ISO for 100, and at f30 (telecentric in place) of your 16 inch SCT prominences require an exposure of around 1/15 of a second. Reinstalling the OD5 white light filter you will see - nothing, nada, zip. Your camera exposure now becomes ~ 6,666 seconds (111 minutes - 1.85 hours) - obviously not practical for a total solar eclipse that usually lasts no more than a few minutes wink.gif

 

However, don't forget the H alpha emission (656 nm) is not the only prominence emission wavelength, you have the H beta (486 nm) for an eclipse, which will be removed by the H alpha filter, increasing the exposure even more for the white light filter use.

 

For hi-resolution images you not only have to deal with the atmosphere as noted by BabyPepper - you now have to deal with the highly magnified movement of the features themselves, which will be considerable over the necessary exposure. This defeats the goal of using the full resolution of the 16.

 

So again while I have not tried this, I look forward to seeing the results of anyone who makes the effort to try.

By the way I was reading in another thread that somebody was using a heat blocking filter available through Edmonds scientific...

https://www.edmundop...-mirrors/11665/
 

Here was one of those filters...  What's your experience opinion on these compared to the red/Yellow rejection filters offered by Daystar/Lunt/Baader.  

Angle of Incidence (°): 0.00 Coating: Hot Mirror, 0°

Substrate:BOROFLOAT® Reflection (%): >95, 750 - 1150nm
Dimensions (mm): 101.6 x 127.0 Surface Quality: 80-50
Thickness (mm): 3.30 Transmission (%): >90, 425 - 675nm
Type: Hot Mirror Dimensional Tolerance (mm): ±0.5
Coating Specification: Surface 1: 0° Hot Mirror
Surface 2: None Wavelength Range (nm): 425 - 1150
Surface Flatness: 4 - 6λ Coating Type: Dielectric



#13 carolinaskies

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Posted 11 September 2019 - 01:59 PM

What you need is a satellite.

Nah... just a few thousand dollars for a full ERF for the 16"  and more than that for the full monty Daystar has with complete solar filter wheel assembly. 



#14 MalVeauX

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Posted 11 September 2019 - 02:07 PM

I highly recommend you try to image convection cells with your 16" in white light first. If you can manage that, often enough, at critical sampling at a wavelength of your choice (highly suggest red wavelengths of course here) in your seeing at that image scale, then you might have some good indication that a full aperture D-ERF, as costly as it will be, would be worth while.

 

Or is this strictly for visual?

 

Thing is, no one makes a 16" D-ERF like this. Basically topping out at 11" right now. So keep that in mind. This is a custom job.

 

Very best,



#15 BYoesle

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Posted 11 September 2019 - 05:51 PM

Hi Paul,

 

Sorry to be so blunt about it - your white light solar filter is good for continuum imaging of the photosphere PERIOD. If you like expending time and effort and prove to yourself that it won't work for the H alpha chromosphere after receiving the advice from others with more knowledge and/or experience, then that's a harmless exercise.

 

But now you're getting into dangerous territory with the following:

 

By the way I was reading in another thread that somebody was using a heat blocking filter available through Edmonds scientific...

https://www.edmundop...-mirrors/11665/

Here was one of those filters...  What's your experience opinion on these compared to the red/Yellow rejection filters offered by Daystar/Lunt/Baader.

 

These filters are nowhere near the optical quality (borofloat w terrible surface flatness 4-6 lambda, SQ 80-50) or type that would need to be employed either as a full aperture or sub aperture filter for solar work - especially with 16 inches of aperture (i.e. using it in front of the secondary, or worse, after). Even the DayStar ERF filters are not an optimum ERF since they only block UV and no IR, and one then must use a supplemental IR blocking filter with them. The Lunt or Baader DERF's are the only real ERFs since they block at both ends of the visible spectrum. None is available in the large sizes your are talking about. A custom 16 inch optical quality filter will cost more than a few thousand dollars, and could be as much as a house. That you don't apparently recognize what an unsuitable optical element these hot mirrors would make is telling. Note that when the catalog states "When using high power illumination, forced air cooling is recommended" it should be a big red flag - these will crack under a significant heat load (i.e. a sub aperture ERF).

 

Depending on how you are implementing it, using the aforementioned Edmund hot mirror for solar telescope ERF use could be disastrous. I highly advise you stick to commercial telescopes and filter systems and not do any Macgyvering - at least until you gain much more expertise and experience with the complex and even potentially dangerous world of solar telescope and filter design.

 

Be safe.

 

Solar Safety.jpg


Edited by BYoesle, 12 September 2019 - 01:31 AM.

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#16 carolinaskies

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Posted 20 September 2019 - 06:28 PM

I appreciate the feedback.  Got the Combo Quark this week but so far haven't had success with seeing prominences through my 80mm scopes.  Being this is the Combo version it doesn't have a built in barlow system so I tried a few variations to try to get some detail.  I used the ST80 stopped down to about 30mm, maybe too far? and used a standard shorty barlow between the 80mm and Quark.  I also tried full aperture with no joy.  I also tried my 80ED F7.5 w/ the barlow which would give around F/15 but no joy either.  BTW I did try my white light filter with the 80ED and got no signal...  will in the future still try the white light glass & Quark with the 16" still for kicks.  

I have yet to try my 152mm/1200mm Meade F/8 which I'll stop down to about 80mm(F/15) and try the barlow for an F/30.  

Wondering if the barlow itself is part of the problem and if I need to get something like an 4x Powermate instead.  Any suggestions? 




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