PST Etalon with a Quark, Log & Results

[Merlin66]

Here's the above DS jpg file in a quick (not perfect!!) run through ImPPG.

Marty_Quark_PST_DS_01_imppg.jpg (141.73 KiB) Viewed 1889 times

[MalVeauX]

Yea, I'm sure I'm aggravating the limb with processing. I'm trying different approaches to see if anything can work without blasting the double limb as bad.

I agree I'm probably still not perfectly tuned on band. It's hard to know where I am with the tuning since there's no guarantee what any particular setting is on either etalon. And the number of combinations of each setting on the Quark versus the PST etalon is a significant number to test. Basically I need to just put my Quark on a setting, then slowly tune through the PST etalon and see real time what happens on the limb. I need some long sessions for this, the weather has not been playing nice.

Hopefully I can test this soon!

Very best,

[Bob Yoesle]

One thing I do notice is that depending on the processing I can "pull" the double edge out of almost any image...

Hi Ken,

For me it was a long learning curve to discover exactly what an on-band image should look like. I still have trouble at times, especially in the typical relatively poor seeing I have, to take the time needed to perfectly tune two etalons, which seems at least 4-6 times more difficult than tuning a single etalon. Perhaps more significantly, in my experience consumer H alpha etalon quality in the past few years seems to have decreased due to needing to make etalons more affordably.

Added to this - at least for my air-spaced etalons - is that changes in barometric pressure and temperature can have subtle but detectable changes in the CWL of the filter system. So while I may start pretty close to exactly on-band, later I may need to make some fine adjustments to optimize the tuning due to these pressure and temperature changes, which can effect both the refractive index of the etalon gap, and change the spacing of the etalon plates themselves via spacer expansion and contraction.

This might be one area where the solid-spaced temperature tuned etalons may prove a little more stable under changing atmospheric conditions. The downside is the lag time in making tuning changes, and perhaps the accuracy of the temperature setting reflected in the wavelength display (if present). On the other hand, I don't really know how sophisticated the temperature regulation of these etalons is, and what if any changing thermal related gap spacing might result in over time.

See if you can pull the double limb out of one or more of these images. They are some of my better unprocessed and minimally compressed jpeg conversions of the 900 mm and 1800 mm FL tiff files out of Registax, using double stacked pre-Meade SM90 etalons:

[marktownley]

Those double stack 90s are sublime Bob. Very Jealous!

[Bob Yoesle]

Thanks Mark - I was lucky to be able to get these etalons when such quality was available and still relatively affordable.

I should note that the above images were wavelet processed in RegiStax6, but had no additional post processing, and the their RG630 ERF's were replaced by a single Baader DERF for improved IR rejection and image brightness.

[bart1805]

Wow, they look way better than all of my processed images. So agree with Mark: jealous!
About the double limb. If there is no double limb visible in the images it is not possible (in my opinion) to make it visible. It simply is not there.
But if you have an image of a normal single stacked etalon, you see the double limb. And if you proces "hard", use a lot of contrast and gamma for example, you can make it disappear. Off course it is still there, but not visible in the processed image. I personally don't really like these kind of images, but that is just a matter of taste.

[MalVeauX]

Heya,

Played around with tuning today a little. Had a chance to see if I could do some tests between clouds, which I was lucky to have some decent seeing and some finally fairly good weather and a nice new sunspot has evolved, so a great way to test tuning. I can't seem to eliminate the double limb. However, I can definitely see differences in the tuning with respect to sunspots, where the double stack removes more of the umbra, and in the single stack the umbra are very visible and dark. Quite interesting.

Single stack (Quark only):





Double Stack (Quark & PST Etalon):





And here's a double stack of the filament and proms (the limb is worse compared to before):



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++++++++++++++++++++++

Here's a limb + prom + new AR example, unprocessed other than stacking and a little histogram/level adjustment to see the limb:

Limb_Example.jpg (123.75 KiB) Viewed 1810 times

Very best,

[marktownley]

The limb shot is excellent Marty. Don't worry about the ghost / residual of the double limb; with the etalons you have you are on peak performance. The only way you are going to improve is by doing what Valery does and try many etalons and cherry pick the best. There's nothing wrong with the images you are getting.

[MalVeauX]

Another go at AR2733 with the Quark & PST Etalon tuning testing.

Here's the limb & prom (Quark & PST etalon):





Here's AR2733 with just the Quark (visible umbra):





Here's AR2733 with the Quark & PST etalon (umbra are no longer visible):





Very best,

[MapleRidge]

Hi Marty...

These recent additions look great, especially the structures in the faint prom.

Well done

Brian

[MalVeauX]

Heya,

Tested some more today with the Quark & PST Etalon.



















Very best,

[MapleRidge]

Marty...

These latest images look great!!!

Brian

[MalVeauX]

More from today with AR2733 & the double stack:











Very best,

[Bob Yoesle]

Now you're cooking Marty! Pretty much right on band to me. The normally processed greyscale bright and dark mottles look exactly as they should, and there is no discernable double limb.

[MalVeauX]

Thanks,

I've marked on the two etalons where to orient them for consistency. I still tweak here and there, but ultimately it seems to be best at this position.

The above were at 10ms exposure time, no gamma (neutral) and gain is running 160 to 200 for these, filling histogram into the 60~70% range.

Very best,

[Astrophil]

Marty, those are really really great images. You have that system working well. Congrats.

Phil

[MalVeauX]

Thanks Phil,

I have the C8 Edge & 214mm tri-band ERF. Just waiting for the filter holding cell to arrive from Germany.

This system will then transfer to that new setup. I will probably try it reversed with the PST etalon with its collimating lenses in the F10 beam of the C8 and then the Quark after, to maybe do a better job (with the blocking filter being last and likely more ideal I would think?).

Very best,

[marktownley]

I think you will do well with the edge HD, your seeing is better than mine.

[MalVeauX]

Hoping so! I love my 6" refractor, but I'd like to use something a little bigger and something color-free for planets and night astrophotography. The big old achromat is great in narrowband, but it's not great for visual spectrum on bright subjects. Can't complain, this 6" telescope was $250!

Very best,

[Valery]

Thanks Phil,

I have the C8 Edge & 214mm tri-band ERF. Just waiting for the filter holding cell to arrive from Germany.

This system will then transfer to that new setup. I will probably try it reversed with the PST etalon with its collimating lenses in the F10 beam of the C8 and then the Quark after, to maybe do a better job (with the blocking filter being last and likely more ideal I would think?).

Very best,

Hi Marty,

C8 Edge will not work properly with PST etalon in it's native confifuration. Back space of this telescope is less than required 200mm+

So, the best is to work as with 6" refractor: Quark Chromosphere will work at F/43 (very nice for narrow bandwidth) + 0,6x reducer + IMX174 camera. You can add PST etalon naked (no it's native lenses).

Good luck.

Valery

[Valery]

Hoping so! I love my 6" refractor, but I'd like to use something a little bigger and something color-free for planets and night astrophotography. The big old achromat is great in narrowband, but it's not great for visual spectrum on bright subjects. Can't complain, this 6" telescope was $250!

Very best,

I see you never looked through a 6" F/8 achromat + ARIES Chromacor-I or II ! They both are gamechangers in such a combination.


Valery

[MalVeauX]

Good to know Valery, thanks, so my configuration will remain as it is here when I move it over to the C8.

I'm sure a Chromacor would be nice. But, at the end of the day, the C8 Edge is more compact (less moment arm) than my huge refractor and has more resolution for imaging purposes.

Very best,

[Astrophil]

Marty, I'm sure you get the C8 working well. Looking forward to seeing your results.

Phil

[MalVeauX]

From this morning with the 150mm and the Quark & PST etalon:









Very best,

[MalVeauX]

Here's some RAW stacks with only histogram stretching and a little deconvolution via IMPPG from the previous data set with no other processing performed. This is the Quark + PST etalon. These are 180 frames stacked each (out of 2000).

prom_ds_crop_01.jpg (89.86 KiB) Viewed 1405 times

prom_ds_crop_02.jpg (114.24 KiB) Viewed 1405 times

Very best,