SM2 Etalon, Primary vs Double Stack Module?

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MalVeauX
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SM2 Etalon, Primary vs Double Stack Module?

Post by MalVeauX » Sat Feb 22, 2020 12:32 am

Hey all,

Sorry if this is confusing. I'm trying to really get a handle on the difference between a primary front mounted Solarmax II 60mm series etalon and a double-stack module etalon of the same series. They look different. I have the SM60II double stack etalon, with verbage that says it should be used with a primary etalon or solarmax scope, etc. But what's the real difference I wonder? When I see some images, the primary front mounted etalon has no rich view tuner the way the DS module does. Then sometimes I see an image of someone using just the SM DS module on its own with a blocking filter. This is confusing.

For example, look at these two options:

https://telescopes.net/store/solar/sola ... uning.html

https://telescopes.net/store/solar/coro ... r-kit.html

They're different, yet ..... are they?

Very best,

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Re: SM2 Etalon, Primary vs Double Stack Module?

Post by DeepSolar64 » Sat Feb 29, 2020 5:15 am

Marty,
I never realized they had two versions of these. Mine is the DS Etalon that has the tuning wheel and a front tuning ring as well. Reading your post I am confused too. Does the DS Etalon mount together with the primary etalon externally like the SMIII does? I didn't know any version of the SMII could do that. My SolarMax II has an internal primary etalon and the DS etalon mounted externally in front. I don't see why any external etalon could'nt be used a a single-stack etalon with a blocking filter.

I know I am not much help and have probably confused you worse. Sorry.

James
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Re: SM2 Etalon, Primary vs Double Stack Module?

Post by MalVeauX » Sun Mar 01, 2020 8:45 pm

Heya,

Yea, still curious.

I tested it the other day, just my double stack etalon on the front of my ED80 without a primary etalon and just my blocking filter. It still tuned and came to focus and all and it was HA features. It didn't look the way a typical etalon looks to me though. I think it may already be slightly tuned off-band to account for the tilt needed for reflection and so the tuning is needed to extend into red, to make up for blue shift from tilting. That may have something to do with what I saw. But I saw chromosphere features with just the DS module, the limb was fine, it was overall fairly bright, but not blindingly bright. From an imaging stand point it cost me about 100 gain when I was using no gain before, give or take a bit. Definitely not something to use on its own. Was just curious if anyone knew the specifics of the double stack difference from the primary etalon since they are different. Lots of weird links out there show the primary but are the double stack, or look like the double stack but are listed as primary....

Very best,

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Re: SM2 Etalon, Primary vs Double Stack Module?

Post by Bob Yoesle » Thu Mar 05, 2020 3:31 am

Hi Marty, you can not rely on retail vendor advertising images to reflect the current model production. Many of them show previous generation models for the current version. I would stick to the manufacturers site for the correct image of the filter production - and this is not even 100% reliable.
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Re: SM2 Etalon, Primary vs Double Stack Module?

Post by Merlin66 » Thu Mar 05, 2020 5:49 am

Marty,
The first link is an original SM60, the second a SM60 II with Rich View Tuning.
I used a couple of SM60 double stacked on an ED80 for many years. No issues.
I now use a combo of SM60II as the “primary” etalon and a SM60 as the DS.
I honestly haven’t experienced any issues, once they are tuned properly.
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Re: SM2 Etalon, Primary vs Double Stack Module?

Post by Marcus444 » Sun Mar 08, 2020 2:28 pm

I agree it’s confusing Marty. And it’s not just a Coronado issue. It appears as if no-one in Europe sells the (white) primary external 60mm Lunt filter on which to double stack with the (red) 60mm fha etalon.
With Lunt’s recent announcement that it is going modular with its solar telescopes - like Coronado - maybe these issues will be solved in the future, though let’s hope both manufacturers will offer primary and double stack external etalons separately without having to buy the parent telescopes too.
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Re: SM2 Etalon, Primary vs Double Stack Module?

Post by marktownley » Sun Mar 08, 2020 4:49 pm

Buying etalons is a lottery, regardless of type.
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Re: SM2 Etalon, Primary vs Double Stack Module?

Post by PDB » Sun Mar 08, 2020 4:59 pm

Sorry Mark but I don't take that statement and don't understand why we still take such an attitude from manufacturares. I know making etalons is not easy, but if you shift quality control to consumers (and hope you sell it to less knowlegdeble people) well that is NO WAY of doing business!

Paul

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