New CaK etalons from Solar Spectrum

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New CaK etalons from Solar Spectrum

Post by Bob Yoesle »

It's now official.

Solar Spectrum has announced the availability of CaK etalon filter systems with FWHM's less than 1 Angstrom.

K Line Solar Spectrum SM.png
K Line Solar Spectrum SM.png (170.85 KiB) Viewed 1260 times
Solar Spectrum.


Due to the limitations of even the most modern interference filter hard-layer depositing, reliable CWL uniformity and bandpasses below 1.5 A have been essentially unobtainable, and just as with H alpha, CaK etalons offer the only filter technology that can reliably achieve sub-angstrom performance and high angular resolution.

While there is the availability of DayStar K line etalons, like the rest of DayStar's current offerings, the Quarks seem problematic as far as CWL and uniformity, and their better quality CaK Quantums are insanely priced: ~$18,000 USD for a 2.0 A FWHM. :shock:

While I don't know the exact prices, Mark said his CaK filters will be similarly priced to his H alpha offerings, which in reality makes him the only affordable source for a quality < 1 A CaK optical filter system.

Mine's ordered :D

Bob


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Re: New CaK etalons from Solar Spectrum

Post by marktownley »

That's exciting! I hope he has a lot of them :D


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Re: New CaK etalons from Solar Spectrum

Post by christian viladrich »

Exciting news Bob !

I wonder what is the peak transmission of these filters. Do you have any data on this ?


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Re: New CaK etalons from Solar Spectrum

Post by Bob Yoesle »

Hi Christian,

I'll have to make an inquiry with Mark, not sure he has a cleaved piece of mica yet. It will be an ~ 0.5 A RG18 etalon in a Housing I have left over from a previous 2 A DayStar CaK T Scanner (and possibly heated if not TEC controlled). It has hard coated blockers from Alluxa.

I'll post an answer when I hear back.


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Re: New CaK etalons from Solar Spectrum

Post by hopskipson »

marktownley wrote: Wed Jan 03, 2024 3:53 pm That's exciting! I hope he has a lot of them :D
While I don’t know how many systems he has on hand I know he sourced a few different sized blocking filters for future orders. With Mark, you have to be patient. I have been waiting for over a year (now that he has sourced a lot of the materials wait time should be shorter) and emails are not answered right away but I know it’s going to be a quality product and the price is reasonable.


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Re: New CaK etalons from Solar Spectrum

Post by Dennis »

Interesting. Hopefully the design is done in mind for 100% imaging and according light throughput for the blockers and polarizers. Otherwise im out.


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Re: New CaK etalons from Solar Spectrum

Post by Bob Yoesle »

Hi Dennis,

I'm confused by the statement "hopefully the design is done in mind for 100% imaging." Do you mean as opposed to visual? Camera sensors are generally much more sensitive than retinas with yellowed eyeball lenses, so that would seem to imply you want less throughput for the blockers and polarizers.

However, these filters incorporate new hard-coated Alluxa blockers with a very high ~ 80% transmission. Additionally, Mark has received some very transparent uncolored mica that makes - in combination with the high T blockers - the less than 1 Angstrom bandpasses practical.

My original DayStar ATM 0.7 A filter from 1976 had such a muscovite mica, and the view was brighter and more uniform than almost any I viewed through since. I really regret having sold it. That's why I'm getting one of these etalons now before that mica becomes less available via incorporation into the Baader / Solar Spectrum H alpha filters. Who knows when more of this high-quality mica will become available again. None will likely be coming out of Russia for quite some time, and that coming out from India and elsewhere is reportedly hit or miss.

Bob


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Re: New CaK etalons from Solar Spectrum

Post by Dennis »

Bob Yoesle wrote: Thu Jan 04, 2024 6:58 pm Hi Dennis,

I'm confused by the statement "hopefully the design is done in mind for 100% imaging." Do you mean as opposed to visual? Camera sensors are generally much more sensitive than retinas with yellowed eyeball lenses, so that would seem to imply you want less throughput for the blockers and polarizers.

However, these filters incorporate new hard-coated Alluxa blockers with a very high ~ 80% transmission. Additionally, Mark has received some very transparent uncolored mica that makes - in combination with the high T blockers - the less than 1 Angstrom bandpasses practical.

My original DayStar ATM 0.7 A filter from 1976 had such a muscovite mica, and the view was brighter and more uniform than almost any I viewed through since. I really regret having sold it. That's why I'm getting one of these etalons now before that mica becomes less available via incorporation into the Baader / Solar Spectrum H alpha filters. Who knows when more of this high-quality mica will become available again. None will likely be coming out of Russia for quite some time, and that coming out from India and elsewhere is reportedly hit or miss.

Bob

Hi Bob,

what i meant was that i hope that the transmission of the system is as high as possible and not compromized (by design) for to make it safe for visual use.
80% for the blockers sounds already very good. Info about the aproximate absolute system transmission will be of help to determine exposure times / signal strength for imaging purposes. Yes, the camera sensors are more sensitive then the human eye, but it doesnt tell me if i can saturate the pixel full well of a certain sensor in a good time.

Apart of this i think this is exciting news and im sure it will be a fine product.

Dennis
Last edited by Dennis on Fri Jan 05, 2024 12:46 pm, edited 1 time in total.


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Re: New CaK etalons from Solar Spectrum

Post by Ljungmann »

I can confirm the very high transmission in my 0.3Å SS filter. Amazing views! My old Del Woods 0.6Å ATM filter (Quantum house now) has an extremely high transmission. Probably a good old high quality clear/light Muscovite. If I compare a newer SE 0.4Å filter and my 0.3Å filter, The SE filter have a low and "boring" transmission. Looks like 50% of the transmission of my SS filter. Looking forward to the new CaK filters.


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Re: New CaK etalons from Solar Spectrum

Post by Bob Yoesle »

I wonder what is the peak transmission of these filters. Do you have any data on this ?
Hi Christian,

Per Mark:

"The ones we checked went from 15% to 5% . This was caused by the difference in shade of the mica. With all mica, the darker it is the lower T and broader Hw with the same coating design. With the high T blockers, I'm thinking there won't be that much difference in transmission than a Ha filter. Outside from the fact that we can't see k-line. So visibly, it may seem dimmer... We are using a UV Polaroid with a wave plate to make a circular Polaroid. So that's the same as an Ha filter."


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Re: New CaK etalons from Solar Spectrum

Post by galaxie427 »

Bob Yoesle wrote: Thu Jan 04, 2024 6:58 pm However, these filters incorporate new hard-coated Alluxa blockers with a very high ~ 80% transmission. Additionally, Mark has received some very transparent uncolored mica that makes - in combination with the high T blockers - the less than 1 Angstrom bandpasses practical.

My original DayStar ATM 0.7 A filter from 1976 had such a muscovite mica, and the view was brighter and more uniform than almost any I viewed through since. I really regret having sold it. That's why I'm getting one of these etalons now before that mica becomes less available via incorporation into the Baader / Solar Spectrum H alpha filters. Who knows when more of this high-quality mica will become available again. None will likely be coming out of Russia for quite some time, and that coming out from India and elsewhere is reportedly hit or miss.

Bob
Thanks Bob for posting this new offering from Mark Wagner and I just want to say that the above insights you shared are also much appreciated.
I'm glad I saw your post since I was considering Mark's CaK filters a while back and now must move forward. :D

Thanks again,
Luka


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Re: New CaK etalons from Solar Spectrum

Post by Dennis »

5%-15% is a good value, thx for the info.


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Re: New CaK etalons from Solar Spectrum

Post by hopskipson »

Just got an update from Mark, my filter is complete and awaiting testing. Of course, he is dealing with lots of rain. My weather hasn’t been favorable either but spring is coming! I have fingers crossed to have it by the end of the month. :D


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Re: New CaK etalons from Solar Spectrum

Post by Dennis »

hopskipson wrote: Fri Feb 09, 2024 6:58 pm Just got an update from Mark, my filter is complete and awaiting testing. Of course, he is dealing with lots of rain. My weather hasn’t been favorable either but spring is coming! I have fingers crossed to have it by the end of the month. :D
Lucky you, i didnt even get a reply to my email 4 weeks ago, asking how much one would be :lol:


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Re: New CaK etalons from Solar Spectrum

Post by hopskipson »

Dennis wrote: Fri Feb 09, 2024 8:24 pm
hopskipson wrote: Fri Feb 09, 2024 6:58 pm Just got an update from Mark, my filter is complete and awaiting testing. Of course, he is dealing with lots of rain. My weather hasn’t been favorable either but spring is coming! I have fingers crossed to have it by the end of the month. :D
Lucky you, i didnt even get a reply to my email 4 weeks ago, asking how much one would be :lol:
Hopefully you won’t have to wait over a year for delivery like me. Try to pm him here or send him another email.
According to Mark they will be similarly priced to the RG H-alpha filters but don’t quote me on that.


James
These pretzels are making me thirsty! (C.C.)
The Quark introduced me to this wonderful side of the hobby and the sun hasn’t disappointed yet.
Solar Equipment: Solar Spectrum RG-18 0.3A, Coronado Solarmax 90mm etalon Isle of Man SN-001, Tuscon SN-380 and Meade SM2, Lunt LS80 DS, Quark Chromosphere, Lunt 2" wedge, 2-Lunt CaK II 1200, Baader 3.8 and 5.0 solar film in 208mm cells, and 3D printed Sol'Ex SHG, Lunt 40mm
Coming Soon: Solar Spectrum CaK II <1A filter
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Re: New CaK etalons from Solar Spectrum

Post by Dennis »

hopskipson wrote: Fri Feb 09, 2024 10:44 pm
Dennis wrote: Fri Feb 09, 2024 8:24 pm
hopskipson wrote: Fri Feb 09, 2024 6:58 pm Just got an update from Mark, my filter is complete and awaiting testing. Of course, he is dealing with lots of rain. My weather hasn’t been favorable either but spring is coming! I have fingers crossed to have it by the end of the month. :D
Lucky you, i didnt even get a reply to my email 4 weeks ago, asking how much one would be :lol:
Hopefully you won’t have to wait over a year for delivery like me. Try to pm him here or send him another email.
According to Mark they will be similarly priced to the RG H-alpha filters but don’t quote me on that.
well that would be just too long for me : )
i was just curious, so you yourself dont know the price yet for yours?


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Re: New CaK etalons from Solar Spectrum

Post by DavidP »

You might contact Bob at Alpine Astronomical about availability


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Re: New CaK etalons from Solar Spectrum

Post by hopskipson »

DavidP wrote: Mon Feb 12, 2024 3:02 am You might contact Bob at Alpine Astronomical about availability
When I tried to order my H-alpha directly from Mark, he didn’t respond to my email until about a month after I ordered it from Alpine. So it took mark about 6 weeks to respond. The H-alpha took a little over the 12 weeks I was quoted for delivery. The price at that time was $3500 plus $400 for the telecentric and the cost of shipping. It was about a third of what Daystar had listed for a similar filter.


James
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The Quark introduced me to this wonderful side of the hobby and the sun hasn’t disappointed yet.
Solar Equipment: Solar Spectrum RG-18 0.3A, Coronado Solarmax 90mm etalon Isle of Man SN-001, Tuscon SN-380 and Meade SM2, Lunt LS80 DS, Quark Chromosphere, Lunt 2" wedge, 2-Lunt CaK II 1200, Baader 3.8 and 5.0 solar film in 208mm cells, and 3D printed Sol'Ex SHG, Lunt 40mm
Coming Soon: Solar Spectrum CaK II <1A filter
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Re: New CaK etalons from Solar Spectrum

Post by Dennis »

hopskipson wrote: Tue Feb 13, 2024 5:18 pm
DavidP wrote: Mon Feb 12, 2024 3:02 am You might contact Bob at Alpine Astronomical about availability
When I tried to order my H-alpha directly from Mark, he didn’t respond to my email until about a month after I ordered it from Alpine. So it took mark about 6 weeks to respond. The H-alpha took a little over the 12 weeks I was quoted for delivery. The price at that time was $3500 plus $400 for the telecentric and the cost of shipping. It was about a third of what Daystar had listed for a similar filter.

Thanks for the info.


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WL: Antlia 500nm/ 3nm, 393 nm/ 3nm
Ca-K: homebrew (includes 2x 1.5A filters, thanks Apollo)
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Re: New CaK etalons from Solar Spectrum

Post by GeorgeIonas »

Good to hear that Mark as some clear mica. My order for a 0.3 angstrom Ha filter placed through Alpine Astro is coming up to 2 years of wait time.


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