Double stack or refurbish my Daystar Quantum?

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cshahar
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Double stack or refurbish my Daystar Quantum?

Post by cshahar » Wed Sep 28, 2016 8:18 pm

Hi Everyone:

I have a 0.4A Quantum PE and I was thinking of refurbishing to get it upgraded to a 0.3A. I was a little concerned that seeing might be an even more critical factor when imaging with a 0.3A filter. Double stacking would give me the option of being able to go back to the original wavelength if I desired. The question is, double stack how? I currently have a 127mm refractor and intend to use a 9.25 SCT next year. So my question is how to double stack with the latter telescope and my Quantum? What double-stacking filter can I use? Can I get it to 0.2A as well? Any help would be appreciated!

-Charles

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Re: Double stack or refurbish my Daystar Quantum?

Post by george9 » Sat Oct 01, 2016 4:44 pm

I do not think you will see too much difference between 0.4A and 0.3A SS, at least not enough to warrant a large expense. Double stacking could have a large effect. There are not a lot of simple options. I use a Lunt DSII unit made for an LS80 in front of my Quark with a good effect. I have a 6inch f/7 refractor. It is notably dimmer than the plain Quark view, but bright enough for visual use. The contrast is astounding.

George

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Re: Double stack or refurbish my Daystar Quantum?

Post by Valery » Sun Oct 02, 2016 1:13 pm

All depends, George. Not all etalons (or their stacks) work same nicely as, for example, your setup.

I never was able to get a good result with double stacking of my two Quarks (with several other etalons). In the same time Mark Townley
always reported that his stacking - Quark + PST work just fine.

And my 0,25A Quark show SIGNIFICANTLY more contrast and finer details images than 0,38A Quark. 0,25A one is signifucantly dimmer
and less uniform than a 0,38A one.
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Re: Double stack or refurbish my Daystar Quantum?

Post by christian viladrich » Sun Oct 02, 2016 6:54 pm

Hello,
Last summer, I tested a group of Daystar etalons (0.6A - 0.5A - 0.4A - 0.3A) on a 250 mm refractor.
Each of these etalons was quite good. The contrast kept on increasing from the 0.6 to the 0.3 A, but the images got dimmer and dimmer.
From my personnal point of view, and for visual observation, I would say the 0.4A is the best balance between contrast and luminosity.
For imaging, I prefer the 0.3A.

As for double stacking the Quantum, I've made some tests with a TO 0.9A :
http://www.astrosurf.com/viladrich/astr ... rast-2.htm
However, the images are very dark.
Very soon, I'll get a 0.9A etalon with 40% peak transmission. Tests will tell if it is OK or not.

George's approach, with the use of an internal etalon in front of the Quark, is certainly a very interesting method.

Christian
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Re: Double stack or refurbish my Daystar Quantum?

Post by george9 » Sun Oct 02, 2016 9:50 pm

I am not sure if I got lucky on the double stack or if there is something about my setup that produces a good result. Pairing an f/7 refractor with the Lunt DSII clearly makes sense because it's transfer lenses were designed for that. At the next solar star party, I will try other DSII units to see if they work the same. May have to wait until NEAF as this weekend was rained out.

But perhaps there is a real advantage to pairing an air-spaced etalon with the Quark instead of another Quark. Mostly likely related to the peak transmission of the DSII being higher than that of the Quark. After all, the Quark is a stand-alone filter that has to block everything that is not H-alpha and also has to keep the SS view dim enough for visual use. The DSII aims to let through as much light as possible; there is no blocking other than the etalon. Also explains why the PST etalon by itself should work.

Also I wonder if there are other reasons, too. Being placed at a significantly different part of the optical train may help. Jen of DayStar warned about inhomogeneity of the solid etalons being a problem in tandem. Also the the possibility of polarizing the light, but I don't detect any polarization in my binoviewer.

Pursuing the higher-transmission 0.9A etalon sounds right.

By the way, when I say a great view, here is what I mean. It is dim compared to SS. The sweet spot is a little smaller than Quark SS but not too bad. The contrast is astounding. Looks like a highly processed image. At Black Forest, a lot of viewers were surprised by it.

I also looked through a Quark that was called 0.3A. Very nice. Very bright, too. No dimmer than mine (my guess is that mine is about 0.5A). Very wide sweet spot and homogeneous. Filaments were pronounced. It was low power, so hard to compare to my 155mm view.

George

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Re: Double stack or refurbish my Daystar Quantum?

Post by Valery » Mon Oct 03, 2016 6:06 am

christian viladrich wrote:
Very soon, I'll get a 0.9A etalon with 40% peak transmission. Tests will tell if it is OK or not.
Christian, what kind of etalon this one is? Air spaced, solid spaced or a filter (like former Baader 1,5A prominence filter) ?


Can you write a more or less detailed report about your tests of DayStar etalons with 250mm refractor? Images? Illuustrations?
This will be every interesting reading for all of us.


Thanks,


Valery
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Re: Double stack or refurbish my Daystar Quantum?

Post by Solar B » Mon Oct 03, 2016 10:26 am

Valery wrote:All depends, George. Not all etalons (or their stacks) work same nicely as, for example, your setup.

I never was able to get a good result with double stacking of my two Quarks (with several other etalons). In the same time Mark Townley
always reported that his stacking - Quark + PST work just fine.

And my 0,25A Quark show SIGNIFICANTLY more contrast and finer details images than 0,38A Quark. 0,25A one is signifucantly dimmer
and less uniform than a 0,38A one.
I'm now looking to try stacking my quark again now that I've got to grips with it for visual use.

Valery I was wondering how you ascertained the Bandwidths of your quarks ?

Brian
" Gentlemen only ever use Refractors "

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Re: Double stack or refurbish my Daystar Quantum?

Post by cshahar » Wed Oct 05, 2016 5:44 pm

Hi:

I am afraid that I don't have the same level of mechanical skills as some of the people on this forum. So how exactly do I doublestack on the Quantum? I have an old PST (with the glass and etalon a bit rusted) that can be used. Do I extract the etalon from the unit? Are there threads on the etalon that will fit into my optical train?

Thanks,

-Charles

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