Daystar Quark Hydrogen Alpha Eyepiece

[Sarah]

I think you're right, Sarah. I'm pretty sure I've seen conflicting apertures along these lines as to when an ERF is needed. I think Luke is wise in planning to try it out on a smaller scope first then work his way up.

Yes Luke and I will be cautious! There also seems to be potentially more of an issue if the scope is tracking the sun for a prolonged period of time.

Here's a link to the Quark manual: http://www.daystarfilters.com/downloads/QuarkManual.pdf

And also some info re the UV/IR cut filter: http://www.daystarfilters.com/inout_article_base/index.php?page=view/article/4/UVIR-Cut-Filter-application-for-Refractors

[michael.h.f.wilkinson]

I would never use coloured dye type ERF anywhere near the diagonal end of the scope. Only interference filters which reflect the unwanted frequencies could be mounted there. Even then I would prefer to have them closer to the objective.

[IanWatkins]

But at that aperture you definitely need to mount an ERF on the front!

I would do that of course, but that only takes seconds to do.

I just like the idea of setting one scope and mount up in the afternoon, do a bit of solar work in WL and Ha, then an evening, night sky session without every moving scopes or mounts about. That would be bliss for me.

[Zakalwe]

A front mounted 150mm ERF ain't cheap though (€915). Still, it'd be a lot cheaper than a 150mm dedicated solarscope!

You could, assuming you have the means to fit it which may mean modifying the OTA, fit a sub-aperture ERF inside the tube. That'd help a lot with the cost.

[GuillermoBarrancos]

I would do that of course, but that only takes seconds to do.

I just like the idea of setting one scope and mount up in the afternoon, do a bit of solar work in WL and Ha, then an evening, night sky session without every moving scopes or mounts about. That would be bliss for me.

That's exactly why I am interested in the quark as well.

[IanWatkins]

A front mounted 150mm ERF ain't cheap though (€915). Still, it'd be a lot cheaper than a 150mm dedicated solarscope!

Indeed, which is why I've been saving for a couple of years for a Lunt 152. But with the seeing we get in the UK I usually stop down the 152mm to 100mm for solar WL anyway (rarely use the full aperture) so a smaller ERF wouldn't hurt. Around 100mm ERF is much cheaper than a 150mm too.

I just like the idea, although I'm not saying I'll do it yet

Cheers

Ian

[michael.h.f.wilkinson]

I am pretty much convinced of going down the route of a 75-80 reflective ERF, which could be (near) front-mounted on my 80mm scopes, and could e internally mounted in a bigger scope. That would also allow using a focal reducer to get a larger FOV, as it would not bear the full brunt of the sun's energy

[Merlin66]

Guys,

Please bear in mind that the amount of solar energy at the end of the "optical" pipeline which is available to image and be received by the eye is minimal.

All Ha scopes work (!??) by removing all other wavelength from the view, just leaving a very "narrow band" of transmission at Ha (6563A).

If the filter system doesn't achieve this, you won't get a usable image.

When you analyse the solar energy curve- there's approx. 1000W/m^2 total energy hitting us, of which 1.6 W/m^2 is the energy around the 10A band at Ha. Drop this by the bandwidth of your average Ha solar scope (0.7A) and you get something like 0.064W/m^2. Based on an aperture of say 150mm this gives a total Ha energy in the region of 0.001W at the eyepiece/ imager.

The real question to ask, is where did the other 999.99% of the incoming energy go??

The obvious answer is that all the filter elements played their part in reflecting/ absorbing it prior to the final blocking filter.

With or without an (additional) ERF in the "pipeline" the end answer must be the same.

Each and every filter component must therefore be able to either effectively reflect (at say >90% efficiency) the incoming energy or at least be capable of absorbing (say, with todays coatings +/- 5%) the energy without cracking/ distorting or failure.

The assumption with the Daystar solid etalon arrangement is that it can safely reflect/ absorb this amount of energy...at least for aperture up to around 120mm.

(I have strongly recommended the use of an in-line ERF in all the larger PST mods....why? I have no accurate knowledge of the optical design other that the fact that the PST etalon can "safely" accept the total input energy from a 40mm objective.)

Hope this helps.

[michael.h.f.wilkinson]

Very true insofar as the Daystar Quark can handle the energy, but what about the diagonal used? I certainly have qualms about that, especially in the case of the little 1.25" one of the ST80.

[GuillermoBarrancos]

And if all that energy is reflected and not absorbed, then where does all that energy go?  My assumption would be back into the optical tube of the scope and build up there?

If I look at the Quark, it doesn't seem to have any vents nor fan or anything to release the heat, so my assumption is that it reflects and not absorb, otherwise the Quark would get uncomfortable hot pretty quickly no?

[michael.h.f.wilkinson]

And if all that energy is reflected and not absorbed, then where does all that energy go?  My assumption would be back into the optical tube of the scope and build up there?

If I look at the Quark, it doesn't seem to have any vents nor fan or anything to release the heat, so my assumption is that it reflects and not absorb, otherwise the Quark would get uncomfortable hot pretty quickly no?

It should go out of the optical tube the way it came through the objective. After all, the objective passed that energy on the way in.

[GuillermoBarrancos]

It should go out of the optical tube the way it came through the objective. After all, the objective passed that energy on the way in.

Good point! And off I go to get some more coffee on this fine early morning.

[Merlin66]

Michael,

I think the minimum would be to screw a "good" UV-IR filter onto the front of the diagonal...note: a mirror diagonal should reflect 98% of the incoming energy, and shouldn't get that hot....

Guillermo,

Yes you're basically correct. Al the reflected light (by far the majority) is reflected backwards into the rear of the objective.

This is why most internal ERF's are slightly tilted to avoid the generation of excessive ghosts.

My understanding is, once the "contents" of the OTA have come up to their "normal operating temperature" there's no adverse effect.

The tuning of the solid Daystar etalon is achieved by heating them - I can only assume Daystar have taken any "energy absorption" into account.

[michael.h.f.wilkinson]

My only concerns are the plastic parts of the cheap ST80 diagonal. I still have a Celestron one somewhere, but I am not totally sure it isn't a prism type. My Denkmeier diagonal does not come to focus with the APM 80mm, and I would not trust the 2" Amici prism in the optical path without protection. But then even if I buy a Daystar Quark with a full-size ERF for an 80mm scope, it is still WAY cheaper than an LS80.

[michael.h.f.wilkinson]

The Celestron diagonal is a prism type. A reflective H-alpha filter (35nm Baader) could be used to protect it I suppose.

[Zakalwe]

It should go out of the optical tube the way it came through the objective. After all, the objective passed that energy on the way in.

That's essentially how sub-aperture systems that people like Lunt use. An unfiltered objective up-front with a smaller Etalon in the light cone. The LLunt L60 has a 60mm singlet objective with a 35mm Etalon. The ERF is 40mm and is mounted about 100mm behind the objective.

I guess that as long as the ERF isn't placed in such a position that the returned IR energy is not focused bang on the objective, then everything will be fine. If the heat was being reflected completely out of the OTA, then even better.

[Joves]

Reading through this thread, one would be mistaken for thinking Daystar are some new, unrecognised brand. Forgive me for being a little blunt, but they are one of the forerunners in consumer solar observing technology, are they not? Would it not be fairly safe to assume that they kind of know what they are doing and have given particular advice regarding the use of their products accordingly?

I'm not for one second suggesting we stop these fine comments or suggestions, as this has fast become possibly my favourite thread at the moment, but are we really that concerned that Daystar don't know what they are talking about or are giving false advice which could possibly destroy equipment and/or, god forbid, send people blind??

[Zakalwe]

Daystar do know what they are talking about, hence their  recommendations that additional filtering is required with apertures >80mm and ERFs with apertures of 150mm and over.

So what's your point?

[Joves]

My point, Zakalwe, is that I'm wondering if the discussion is based on us being concerned that we are being given the wrong advice by Daystar or if we are discussing the need for ERF's and such more for discussions sake?

What's your point?

[GuillermoBarrancos]

My point, Zakalwe, is that I'm wondering if the discussion is based on us being concerned that we are being given the wrong advice by Daystar or if we are discussing the need for ERF's and such more for discussions sake?

What's your point?

Not at all.

But there is nothing wrong by taking some extra steps.

One can never be too safe! Especially not when it comes to solar observing!

That is the point in the discussion.

Nothing specifically towards Daystar as brand.

And I also already copied over the extra advice in the topic pages back, that was posted by Daystar on CN.

[Joves]

Thanks Guillermo.

Was a genuine question. I've ordered a chromosphere model and wondered if I should be adding an ERF to be sure. The tone of my original post was suggesting that I'm pretty confident Daystar know what they are doing, by the way.

Thanks again.

[Zakalwe]

Thanks Guillermo.

Was a genuine question. I've ordered a chromosphere model and wondered if I should be adding an ERF to be sure. The tone of my original post was suggesting that I'm pretty confident Daystar know what they are doing, by the way.

Thanks again.

I see that on their web-page they are saying that ALL scopes now need an ERF.

http://www.daystarfilters.com/Quark.shtml

Has this changed since launch?

Their  initial flyer states a UV/IR filter is needed for apertures >80mm and an ERF is only required on all scopes when tracking the Sun.

http://www.daystarfilters.com/downloads/QuarkFlyer.pdf

[Joves]

Hmmm... That's interesting. It seems they are referring to the UV/IR cut filter as being the ERF. I think I recall seeing this notification on the side of their webpage a few days ago. I wonder if they're suggesting that even apertures of less than 80mm really should use an ERF or if that is general advice for all of their filters as a kind of disclaimer?

[Zakalwe]

They are saying that all Quarks need a ERF  "All DayStar Hydrogen a filter assemblies need to be used in conjunction with a lens cover and Energy Rejection Filter."

 

I don't understand the piece about a lens cover though?

[allcart]

That notice appears on the Daystar hydrogen alpha products page as well. I think its refering to the other Ha filter assemblies they sell. I don't Know what they mean by covers either.