PST Etalon with a Quark, Log & Results

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Re: PST Etalon with a Quark, Log & Results

Post by MalVeauX »

There are places where I can see a double-limb, others it's gone. It definitely can be made more apparent with different processing. I prefer a darker more contrasty surface, but it's difficult to do that without wrecking the limb with it. I wish it were easier to way under-example and simply lift proms and the limb, but due to the transmission levels, the amount of gain being used, this seems to not work for this particular setup, at least yet. It may be a processing thing on my end that I have to figure out.

Very best,


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Re: PST Etalon with a Quark, Log & Results

Post by Bob Yoesle »

Hi Marty,

In some of your most recent images I'm seeing just a hint of the double limb, which is not obtrusive. In others I'm seeing processing artifacts, not the double limb of the photosphere:

M Wise highlight.jpg
M Wise highlight.jpg (241.96 KiB) Viewed 8573 times

Note the irregular hard edge appearance all along the limb and at the indicated locations...
Love these raw stacks Marty! But, then you can probably tell from the images I post I err on that side of things with my processing...
Mark I don't think you are in "err." I've been thinking about this for awhile. Here's my thoughts on the subject.

I guess it comes down to what is the purpose of posting images on these forums to begin with. With all due respect to Alan Friedman (a very talented graphic artist by trade - https://avertedimagination.squarespace.com/), his introduction of using colorized inverted (negative) disc images and positive prominence images made for dramatic and colorful "artistic impressions," but do not look anything like the Sun. They also made single stacked images perhaps somewhat "better looking" without the discontinuity at the limb where limb darkening runs into the bright ring of chromosphere - likely their original purpose. This is essentially hiding an imaging system defect in order to present "pretty pictures." To me it seems a little unfortunate that the forums are now awash in this faux imagery, giving many beginners an untrue version of reality, and is at odds to some degree with the principles of scientific accuracy.

I'd compare what is seen so often to the equivalent posting pictures of your family (sometimes ad nauseum) on social media like this:

FamilyGalleryBW2.jpg
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Or not to be sexist, but most of the folks on this forum are men. How many find one of the most beautiful of women to ever have walked the Earth attractive inverted and contrast enhanced, but with her eyes left normal?

Sophia.jpg
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Unless you're a fan of Andy Warhol, it doesn't do much for me. Not that occasionally an inverted or altered image isn't sometimes (sparingly) useful. From my perspective, the positive disc with negative prominences is instructive by demonstrating that prominences and the disc filaments are in reality one in the same phenomena, and that dark details on a light background are sometimes easier for the eye to perceive (I don't find this as true for the disc, if at all):

Filaproms full disc.jpg
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Off soapbox, thanks for looking, and of course your mileage - and opinion - may vary.


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Re: PST Etalon with a Quark, Log & Results

Post by MalVeauX »

Heya,

Rotten weather lately. I got to do some more tests. This time, I revisited doing a full disc with the Quark & PST Etalon. I must have totally missed the boat because I guess I never tried putting a 0.5x focal reducer on the standard 1.25" nose extension after the tilt adapter (effectively moving it farther away from the sensor) and inserting that into the Quark's eyepiece holder, but also tried it with the PST etalon with apdaters in place and a 2" to 1.25" adapter and it too worked. I was able to get a full disc FOV out of a ST80 refractor with both the Quark & PST etalon with the 0.5x focal reducer and the IMX174 sensor size. I've had this for so long and yet I guess I just never tried putting the reducer on that side of the insert, and always had it closer to the sensor. Well dur dur dur, now I can do full discs no problem with my wee ST80.

Full Disc Double Stack Imaging train left to right:

ASI174MM -> ZWO Tilt Adapter -> 1.25" Nose -> GSO 0.5x 1.25" Focal Reducer -> 2" to 1.25" adapter -> PST Etalon & Adapters -> Quark with 2" eyepiece holder -> 2" 35mm Extension -" 2" 80mm Extension (with 2" UV/IR block filter threaded on nose) -> GSO 2" Crayford focuser -> ST80 (400mm F5) -> Aperture Mask of 60mm (F6.67)
FullDisc_Quark_PST_DS_02152019.jpg
FullDisc_Quark_PST_DS_02152019.jpg (56.61 KiB) Viewed 8532 times
Here's the FOV, parameters, histogram and real time view in FireCapture:
ScreenShot_FullDisc_Quark_PST_DS_ST80_FR_02152019.jpg
ScreenShot_FullDisc_Quark_PST_DS_ST80_FR_02152019.jpg (139.52 KiB) Viewed 8532 times
Here's a processed result (from a single exposure, no gamma):

Image

Now, back to high res. Here's the 150mm with the Quark & PST Etalon as normal, with the IMX174 & 0.5x focal reducer.
SolarSetup_02152019.jpg
SolarSetup_02152019.jpg (57.18 KiB) Viewed 8532 times
Here's the parameters, histogram, flat field applied and real time view in FireCapture:
ScreenShot_HighRes_02152019.jpg
ScreenShot_HighRes_02152019.jpg (177.23 KiB) Viewed 8532 times
Here's today's filament & plage area near some limb prominences, I think I got the tuning better this time. Presented in normal view and inverted. This is the result of a single exposure, no gamma.

Image

Image

Very best,


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Re: PST Etalon with a Quark, Log & Results

Post by marktownley »

Looks good Marty!


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Re: PST Etalon with a Quark, Log & Results

Post by MalVeauX »

Had a little time this morning to get some testing between clouds.

150mm with the Quark & PST Etalon:

Image

Image

Image

Image

ST80 masked to 60mm with Quark & PST Etalon:

Image

Image

Very best,


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Re: PST Etalon with a Quark, Log & Results

Post by MalVeauX »

Managed a little full disc time this morning with the Quark & PST Etalon together:

Image

Image

Very best,


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Re: PST Etalon with a Quark, Log & Results

Post by MalVeauX »

Heya,

I tried another setup today at two scales, full disc and a large scale. These are the Quark & PST Etalon together. One with the ST80 and one with a C8 Edge.

Image

Image

Image

Image

Very best,


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Re: PST Etalon with a Quark, Log & Results

Post by MalVeauX »

Here's the limb today with the Quark & PST etalon with respect to tuning out the double limb:

Image

Image

Image

Image

Earth Scale:
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Very best,


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Re: PST Etalon with a Quark, Log & Results

Post by MalVeauX »

Toying around with some of the data to see what works best.

Here's one imaging run, 2000 frames, stacked 1250 of them. I've compared things from 60, 100, 180, 360, 500, 750, 1000, 1250, 1500, 2000 frames just to mess around with things. Playing around with different approaches to deconvolution and unsharp masking in IMPPG. For this one, it's lower on the deconvolution and harder on the unsharp mask. No other processing.
Unprocessed_1250frames_02272019.jpg
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Very best,


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Re: PST Etalon with a Quark, Log & Results

Post by MalVeauX »

Does anyone know if a PST etalon can be stacked with a 2nd PST etalon without collimating lenses, like above, or do they both need to have their collimating lenses. Any ideas about the advantages with or without the 2nd set of collimating lenses?

I rarely see PST double stacks. I've seen a few here and there, they seem to be very fussy to get right. Curious if it would be worth trying a 2nd etalon since I already have one and adding a 10mm blocking filter.

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Re: PST Etalon with a Quark, Log & Results

Post by marktownley »

Try it, but I bet reflections will be a PITA...


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Re: PST Etalon with a Quark, Log & Results

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Re: PST Etalon with a Quark, Log & Results

Post by MalVeauX »

Heya,

Been a while, figured I'd update this. The transmission was pretty low, so it made larger imaging scales more difficult. So recently, just to re-visit this, I went to a smaller scale.

This is my ST80 (80mm F5) with full aperture, so the Quark results in an F21 beam. This is not ideal, however, it seems to be a better match for the IMX174 pixels and for mixing with the PST etalon. Not sure why. PST Etalon without the collimating lenses after that. ASI174MM inserted, without any focal reducer. Transmission was better, but still quite low. This is at 10ms, gain 155 (38%) and gamma was neutral (off). It was fairly noisy and had pronounced newtonian rings. I couldn't get a flat frame to save my life (even with a tilt adapter). Processed most of it away in post.

Anyhow, the limb seems pretty good. Maybe the best I've been able to tune together so far? I likely will not pursue this farther than this. I think as a small scale double-stack option, it's viable, but far from optimal. But, I figured I would stop here for now on this note, to show the limb and how things are going with this experiement.

This is from today, AR2739 coming up to the limb.
80mm_Quark_PSTetalon_DS_181frames_04202019.jpg
80mm_Quark_PSTetalon_DS_181frames_04202019.jpg (130.34 KiB) Viewed 8112 times
Solarsetup_05_04202019.jpg
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Very best,


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Re: PST Etalon with a Quark, Log & Results

Post by Bob Yoesle »

That's really very good Marty, and better than a lot of others I've seen with the more recently made filter systems.


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Re: PST Etalon with a Quark, Log & Results

Post by MalVeauX »

Bob Yoesle wrote: Sun Apr 21, 2019 7:29 pm That's really very good Marty, and better than a lot of others I've seen with the more recently made filter systems.
Thank Bob,

It's amazing how minute nudges on the etalon, rotation, and the difference it makes to have a F28 beam, F35 beam, F42 beam, and even F21 beams has on the end result. I'm not sure what the true difference is, but at F35~F42 I was never able to make it work, but at the looser F21 it works. I can't explain it. Maybe I'm missing something.

Unfortunately the transmission is just so low, but that may be copy variation on top of things.

I tested this morning to see differences in transmission with two sensors. I tested an IMX174 & IMX178 to see if binning and different quantum efficiencies might help. After calculations just for fun, I figured the IMX178 would be less "fast" for imaging, and in reality, it was. The larger pixels of the IMX174 are much faster. This morning, just binning 2x2, I was able to fill my histogram with this double stack at 10ms, 45 gain, no gamma. I could image with that. But, the under-sampling was severe and the limb was just a smear of pixels, so I abandoned that as an option.

I'll be comparing this to a Solarmax 60mm Double Stack maybe in the next week or so, to put the final nail in the coffin.

Very best,


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Re: PST Etalon with a Quark, Log & Results

Post by minhlead »

MalVeauX wrote: Sun Apr 21, 2019 8:01 pm
Bob Yoesle wrote: Sun Apr 21, 2019 7:29 pm That's really very good Marty, and better than a lot of others I've seen with the more recently made filter systems.
Thank Bob,

It's amazing how minute nudges on the etalon, rotation, and the difference it makes to have a F28 beam, F35 beam, F42 beam, and even F21 beams has on the end result. I'm not sure what the true difference is, but at F35~F42 I was never able to make it work, but at the looser F21 it works. I can't explain it. Maybe I'm missing something.

Unfortunately the transmission is just so low, but that may be copy variation on top of things.

I tested this morning to see differences in transmission with two sensors. I tested an IMX174 & IMX178 to see if binning and different quantum efficiencies might help. After calculations just for fun, I figured the IMX178 would be less "fast" for imaging, and in reality, it was. The larger pixels of the IMX174 are much faster. This morning, just binning 2x2, I was able to fill my histogram with this double stack at 10ms, 45 gain, no gamma. I could image with that. But, the under-sampling was severe and the limb was just a smear of pixels, so I abandoned that as an option.

I'll be comparing this to a Solarmax 60mm Double Stack maybe in the next week or so, to put the final nail in the coffin.

Very best,
Wow I found this gems of a post hidden under mountains of content and thank you Marty for making such a detailed and meticulos log on your endeavour with the PST-Quark DS. This will be the lodestar for me on mine.
I have a few question before diving head first into this.
1. How do you rate this particular PST and Quark that you used on the mod (FWHM, sweetspot size ie. How big of a sweet spot did you get, say on a imx174 sensor?)
2. Did the sweet spot size of the PST increased in comparing with if you use in in the original scope? (I assume it would since it's in a telecentric beam with high F ratio but I am not sure)
3. How is you transmission loss compared to just the Quark (I see that you got 10ms exposure with the double stack but how much did you use before double stack?)
4. How did you tune the PST relative with the Quark (i can see you marked the rotation, did you use some kind of tilting mechanism on your PST? Did you aim for the darkest image possible or just tune it until highest contrast?
5. How is the reliability of the mod, after a long time use any problem arise?
Sorry for the many question and thanks again for your dedication!


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Re: PST Etalon with a Quark, Log & Results

Post by marktownley »

minhlead wrote: Tue Dec 14, 2021 12:51 am Wow I found this gems of a post hidden under mountains of content and thank you Marty for making such a detailed and meticulos log on your endeavour with the PST-Quark DS. This will be the lodestar for me on mine.
I have a few question before diving head first into this.
1. How do you rate this particular PST and Quark that you used on the mod (FWHM, sweetspot size ie. How big of a sweet spot did you get, say on a imx174 sensor?)
2. Did the sweet spot size of the PST increased in comparing with if you use in in the original scope? (I assume it would since it's in a telecentric beam with high F ratio but I am not sure)
3. How is you transmission loss compared to just the Quark (I see that you got 10ms exposure with the double stack but how much did you use before double stack?)
4. How did you tune the PST relative with the Quark (i can see you marked the rotation, did you use some kind of tilting mechanism on your PST? Did you aim for the darkest image possible or just tune it until highest contrast?
5. How is the reliability of the mod, after a long time use any problem arise?
Sorry for the many question and thanks again for your dedication!
Hi Minh,

Sweetspot only exists in a collimated beam, it's size is a function of aperture size versus etalon size. The bigger the objective relative to etalon, the
smaller the sweetspot. Bigger sweetspot is preferable. The bigger the chip on the camera the more the region out of the sweetspot it will show, so, cropping / ROI may be the way to go.

To tune the PST etalon you just turn the knurled ring as you would normally. My experience is that tuning the etalon imparts some tilt as if the tuning is too extreme (in this configuration) you get a band, trick is to get the band central so that it covers the fov. I just tuned for the darkest filaments and avoided off band features.

I've been doing this for several years now and there are no reliability issues.

Mark


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Re: PST Etalon with a Quark, Log & Results

Post by christian viladrich »

Hi Minh,
As an additional information, in a collimated beam the problem is non uniformity of the etalons (the sweet spot formation is only in collimiated beam). It might be that each of the two etalons are good as a single stack, but not good as a double stack because non uniformity of the CWL goes in different directions.
The only way to know is to try it ...


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Re: PST Etalon with a Quark, Log & Results

Post by minhlead »

Great informations, thanks Mark and Christian.
@Christian: if that happens can I solve it by rotating the 2 etalon relative with each other and find a spot that have the un-uniformities matched?


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Re: PST Etalon with a Quark, Log & Results

Post by christian viladrich »

minhlead wrote: Wed Dec 15, 2021 11:30 am Great informations, thanks Mark and Christian.
@Christian: if that happens can I solve it by rotating the 2 etalon relative with each other and find a spot that have the un-uniformities matched?
Indeed, this is part of the tuning. Then you will find out if the result is good enough or not.
For example, I stacked a Quantum 0.6A with two different PST (only one at a time). One double stack combination was acceptable, the other very bad (because of non uniformity).


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Re: PST Etalon with a Quark, Log & Results

Post by rsfoto »

MalVeauX wrote: Sun Apr 21, 2019 8:01 pm
Bob Yoesle wrote: Sun Apr 21, 2019 7:29 pm That's really very good Marty, and better than a lot of others I've seen with the more recently made filter systems.
Thank Bob,

It's amazing how minute nudges on the etalon, rotation, and the difference it makes to have a F28 beam, F35 beam, F42 beam, and even F21 beams has on the end result. I'm not sure what the true difference is, but at F35~F42 I was never able to make it work, but at the looser F21 it works. I can't explain it. Maybe I'm missing something.

Unfortunately the transmission is just so low, but that may be copy variation on top of things.

I tested this morning to see differences in transmission with two sensors. I tested an IMX174 & IMX178 to see if binning and different quantum efficiencies might help. After calculations just for fun, I figured the IMX178 would be less "fast" for imaging, and in reality, it was. The larger pixels of the IMX174 are much faster. This morning, just binning 2x2, I was able to fill my histogram with this double stack at 10ms, 45 gain, no gamma. I could image with that. But, the under-sampling was severe and the limb was just a smear of pixels, so I abandoned that as an option.

I'll be comparing this to a Solarmax 60mm Double Stack maybe in the next week or so, to put the final nail in the coffin.

Very best,
Hi Marty,
... It's amazing how minute nudges on the etalon ...
Good that you mention it. As you perhaps know I have a stepper motor for changing the angle of my double stacked SM60 etalon. In order to move the a full turn of the lead screw I need to make 5120 steps having a pitch of 0.794 mm, it is a 32tpi threaded screw #6-32 UNC

I have seen that moving just 64 steps I already see a change of the sweet spot position. One step in my setup is a movement of 0.155 micron or better said 0.000155 mm which means I only move 64 x 0.155 for a change ...

Just a side note from my part :)


regards Rainer

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