Daystar Quark Hydrogen Alpha Eyepiece

[michael.h.f.wilkinson]

Hmm, my understanding was to go as narrow in band as you can for good prominence detail. I used to have a .8 daystar manual tune and while good , I'd like better nowadays. Why would you not just buy the chromosphere (narrowest) version and be done ?

I gather that a wider band admits more light, so the proms are more prominent (sorry, couldn't resist). Nonetheless I agree that the narrower band seems more interesting

[Zakalwe]

The optical design of the quark got me thinking. What they have essentially done is put the etalon in at the rear end of the optical train, rather than at the front as in the LS35 and many Coronado scopes, or in the middle, as in most Lunts. This is perfectly possible if the distance between image plane and rear element of the tele-centric lens system is sufficiently large.   

As long as the front collimating lens is within the focal plane then it should be OK. That lens will take the converging lightbeam and collimate it into a near parallel beam which is necessary to get the Etalon to work.

 It also got me thinking along "LS35 Mod" routes again. Why not put the 35mm ERF in front of my B1200 blocking filter diagonal, and put a tele-centric system (like my PowerMate or TeleXtenders) behind it. You could even cobble together a (non achromatic, no need for it) tele-centric of sufficient size from old objective lenses of a pair of bins I have lying around, and a simple negative lens (can be small). Place the etalon with its tilt tuner behind that and attach the helical focuser from the LS35 behind it. Due to the larger blocking filter, full-disk images could be obtained for much larger focal lengths (so I could use the APM 80mm F/6 easily, but bigger scopes are also possible). This would not give the narrow passband of the Quark (which does seem more attractive now), but it might be a relatively cheap experiment to set up (I have most if not all components). 

I guess that the issue might be using a big objective with such a small ERF?

[Merlin66]

There has been some very "active" discussions on the Solar Chat site about the merits (or otherwise) of using an etalon (bare PST, Lunt 35 Lunt 50 etc. in a telecentric (or fully collimated) beam.

The possibilities are there to achieve a 0.7A bandwidth system.

Re APO v's achromat etc. it's not just the chromatic aberrations but also the "possible" spherical aberrations which may affect lower quality achromats.

I have to say, I do have a concern regards the Quark arrangement - with minimal ERF protection. For me a UV-IR filter just doesn't cut it.

[skybadger]

The optical design of the quark got me thinking. What they have essentially done is put the etalon in at the rear end of the optical train, rather than at the front as in the LS35 and many Coronado scopes, or in the middle, as in most Lunts. This is perfectly possible if the distance between image plane and rear element of the tele-centric lens system is sufficiently large.  It also got me thinking along "LS35 Mod" routes again. Why not put the 35mm ERF in front of my B1200 blocking filter diagonal, and put a tele-centric system (like my PowerMate or TeleXtenders) behind it. You could even cobble together a (non achromatic, no need for it) tele-centric of sufficient size from old objective lenses of a pair of bins I have lying around, and a simple negative lens (can be small). Place the etalon with its tilt tuner behind that and attach the helical focuser from the LS35 behind it. Due to the larger blocking filter, full-disk images could be obtained for much larger focal lengths (so I could use the APM 80mm F/6 easily, but bigger scopes are also possible). This would not give the narrow passband of the Quark (which does seem more attractive now), but it might be a relatively cheap experiment to set up (I have most if not all components).

What you are describing is the daystar configuration - etalon after telecentric for best etalon performance. All the quark is doing is wrapping a t-scanner with collimator into a single unit at a very nice price point. Also my reading of use of rtf suggests you only need an it hot mirror at the front of large scopes.

[GuillermoBarrancos]

There has been some very "active" discussions on the Solar Chat site about the merits (or otherwise) of using an etalon (bare PST, Lunt 35 Lunt 50 etc. in a telecentric (or fully collimated) beam.

The possibilities are there to achieve a 0.7A bandwidth system.

Re APO v's achromat etc. it's not just the chromatic aberrations but also the "possible" spherical aberrations which may affect lower quality achromats.

I have to say, I do have a concern regards the Quark arrangement - with minimal ERF protection. For me a UV-IR filter just doesn't cut it.

You can always put an ERF in front.

For example, to keep costs Down and still have an APO. A combination of for example a Evostar 100ED (or 120ED), 90mm ERF and Quark is a very cost effective and powerful combo. Less than a third of the price of for example a Lunt100.

[michael.h.f.wilkinson]

There has been some very "active" discussions on the Solar Chat site about the merits (or otherwise) of using an etalon (bare PST, Lunt 35 Lunt 50 etc. in a telecentric (or fully collimated) beam.

The possibilities are there to achieve a 0.7A bandwidth system.

Re APO v's achromat etc. it's not just the chromatic aberrations but also the "possible" spherical aberrations which may affect lower quality achromats.

I have to say, I do have a concern regards the Quark arrangement - with minimal ERF protection. For me a UV-IR filter just doesn't cut it.

I would agree the absence of a proper ERF is worrying. That is why I would put an ERF in front of the blocking filter and diagonal assembly, but behind the objective. The 35mm ERF is a touch smaller than the 50% of full aperture which is "received wisdom", but I could fist stop down the 80mm to just 70, and check the temperature of the ERF with some probe. If the temperature is reasonable, I could remove the aperture stop and check again. A slightly bigger ERF could be obtained if I move to a bigger scope design, but I could start with either the ST80 or the APM 80 at 70mm aperture.

I would go for the APM rather than the ST80, simply because it has a 2" focuser, which makes life much easier in this mod. The better optical quality (apart from chromatic correction) is another reason to prefer it. Having said that, a singlet lens of really good optical figure could probably also outclass a low-grade achromat. Given the small market for such lenses, it is probably cheaper to use one of the many available quality lenses.

A final reason for using the APM 80mm is that I might then have a reason to get rid of this extra OTA.

[michael.h.f.wilkinson]

What you are describing is the daystar configuration - etalon after telecentric for best etalon performance. All the quark is doing is wrapping a t-scanner with collimator into a single unit at a very nice price point. Also my reading of use of rtf suggests you only need an it hot mirror at the front of large scopes.

Yes, precisely, I am describing the quark's configuration. The only difference is that I do want to include an ERF in the optical train, because the lack of one (just a UV/IR cut filter) makes me VERY nervous

[Luke]

Video from Sean, "Setting up and using the Daystar Quark," on YouTube:

http://www.youtube.com/watch?v=nEYCC8mDL9s

One interesting thing is that Sean mentions there may be a version in a year or so with a 2x Barlow rather than 4.3x. He mentions this after saying that the current one is designed for refractors from F4 to F9, and is not so ideal for say an F15 scope (though it still can be used) because of very high mag or possibly dark image. I wonder if the 2x version would only be designed for say F10 upwards?

I have been thinking about a solution for higher res stuff than my SolarMax 60 and the most likely option seemed to be the 90mm SolarMax etalon, which with a blocking filter would come in at over £3k and would be a single stack (okay for me for imaging but for visual I'd rather have double). And I have to wonder whether it is worth £3k to me when my 60 was closer to £1k and would probably get used more still than the 90 (due to being more grab-and-go and 60mm not being too demanding of viewing conditions).

Interesting times!

[skybadger]

Put yourself on the lucky position of having bought the daystar solar system filter of multiple widely separated wavelength s - then you cannot use an e r f at all......

[Joves]

Just when I thought spending could ease up for a little while!

This seems like a fantastic option. If I have my calculations correct, used in my TV76 with its 480mm FL, coupled with a 24 Panoptic, it'll be pushing out 84x mag with a TFOV of 48.5 arc minutes. This sounds about ideal for full disk visual and would surely give a vastly superior view to my much beloved PST?? Of course, I could still get more than a full degree with the 21mm Ethos, but I reckon that sitting on top of the quark might be a bit much for the little TV76.

Biggest decision seems to be which one to get. Being that I already have the PST which shows proms quite effectively, I think the chromosphere version seems to be the way to go. It really isn't that much more expensive than buying the double stack module for the PST, but on a scope with almost twice the aperture and obviously better glass. What's the comparable alternative... A Lunt LS80 PT? A great scope no doubt, but at $4700, probably not justifiable for me.

I wonder how the views through this compare in terms of detail and tunability. Also, perhaps a naive question (or I haven't read the literature thoroughly enough), but are these likely to be subject to having to adjust the view for a sweet spot like the PST?

All in all, a pretty exciting looking product.

Aaron

[Pig]

Aaron,

In the "U-Tube" link posted by Luke earlier in the thread  It does appear that there is an element of tuning required. The guy presenting talks a little about it toward the end of the demonstration, he suggests moving the heater adjustment to the required position to suit the conditions.

[Luke]

I ordered the Chromosphere Quark from SCS Astro, I'll do a review and post piccies when I get my hands on it. It looks a winner to me

The 4.3x Barlow I think is fine, hopefully around full disc with the right eyepiece and a short focal length refractor. I would ideally like to observe at a lower power than full disc as well, but really, I think this is a compromise well worth making given the spec and price. Imaging-wise, I can switch it between three different refractors to vary the focal length, and it should kick in nicely where my SolarMax 60 starts to run out of puff

Will it affect the pricing of the competition? I wonder if it already did with the Lunt 50...

[Merlin66]

Typically proms are "easier" seen in wider bandwidths - the 0.7A is good for proms.

Most Ha single etalon scopes still give around 0.7A for surface viewing - and the results are very good.

The double stack bring the throughput efficiency down (about 50% the light transmission) and gives a 0.5A bandwidth BUT dramatically improves the surface contrast and detail.

Daystar seem to have "hedged" their bets and offer the same as a single stack (proms) and a double stack (chromo)

[Merlin66]

Michael,

Your comment:

""

The 35mm ERF is a touch smaller than the 50% of full aperture which is "received wisdom"

""

I'd love to know were this originated. I've been unable to source ANY material to support this "urban myth"

(It obviously has a possible impact on the numerous PST mods I do - I'd like to be able to explain the issue clearly based on optical criteria)

[michael.h.f.wilkinson]

Just when I thought spending could ease up for a little while!

This seems like a fantastic option. If I have my calculations correct, used in my TV76 with its 480mm FL, coupled with a 24 Panoptic, it'll be pushing out 84x mag with a TFOV of 48.5 arc minutes. This sounds about ideal for full disk visual and would surely give a vastly superior view to my much beloved PST?? Of course, I could still get more than a full degree with the 21mm Ethos, but I reckon that sitting on top of the quark might be a bit much for the little TV76.

Biggest decision seems to be which one to get. Being that I already have the PST which shows proms quite effectively, I think the chromosphere version seems to be the way to go. It really isn't that much more expensive than buying the double stack module for the PST, but on a scope with almost twice the aperture and obviously better glass. What's the comparable alternative... A Lunt LS80 PT? A great scope no doubt, but at $4700, probably not justifiable for me.

I wonder how the views through this compare in terms of detail and tunability. Also, perhaps a naive question (or I haven't read the literature thoroughly enough), but are these likely to be subject to having to adjust the view for a sweet spot like the PST?

All in all, a pretty exciting looking product.

Aaron

With the size of its blocking filter (according to the specs), you would not quite get a full disk at 480mm focal length (450 mm max according to the flyer).

[michael.h.f.wilkinson]

Michael,Your comment:""The 35mm ERF is a touch smaller than the 50% of full aperture which is "received wisdom"""I'd love to know were this originated. I've been unable to source ANY material to support this "urban myth"(It obviously has a possible impact on the numerous PST mods I do - I'd like to be able to explain the issue clearly based on optical criteria)

I got this advice from several people (from the PST-mod crowd) when I was pondering an LS35 mod. Several PST mods have an ERF behind the objective, and various people noted that an ERF larger than 50% full aperture worked. Sunlight is concentrated less than 4x at that size, so should be OK. Having said that, a Herschel wedge gets the full blast and survives. As the ERF reflects most energy away, it should be OK at smaller sizes as well. I would not advocate putting the ERF at exactly 50% of the focal length of the scope, because that would focus the IR/UV solar image on the objective. given that the objective does not absorb much, it might be OK, but the idea makes me uneasy.

[Merlin66]

Sorry Michael, I mis-read your post....

Yes. I was part of the drive for a >50% ERF on the basis of absolute safety.....

I was distracted by other comments (elsewhere) were the ratio of the size of the etalon should be 50% of the donor aperture "for maximum performance and minimal "sweet spot"".

Sorry.

[michael.h.f.wilkinson]

Sorry Michael, I mis-read your post....Yes. I was part of the drive for a >50% ERF on the basis of absolute safety.....I was distracted by other comments (elsewhere) were the ratio of the size of the etalon should be 50% of the donor aperture "for maximum performance and minimal "sweet spot"".Sorry.

No worries. The etalon size is always a matter of compromise. In the case of a telecentric system the passband is uniform over the entire etalon, but the bandwidth depends on the focal ratio of the system. Thus, for a given image scale at the etalon (which determines the area of the solar disk you can image) a smaller aperture (slower focal ratio) will give a smaller effective passband. At some point the reduction of bandwith does not increase with focal ratio anymore depending more on the finesse of the etalon than the divergence in angles of the beam of light at that point. Perhaps the "50% of aperture) comes from considerations of full disk size on the etalon combined with some optimal focal ratio

[Joves]

Aaron,

In the "U-Tube" link posted by Luke earlier in the thread  It does appear that there is an element of tuning required. The guy presenting talks a little about it toward the end of the demonstration, he suggests moving the heater adjustment to the required position to suit the conditions.

Thanks Shaun.

Yes, I noticed there was a tuning dial. According to the flyer, if I'm reading correctly, it can be dialled in increments of 0.1A. I guess I'm wondering if it's as easy to fine tune as the etalon tuning dial on the PST.

[Joves]

I ordered the Chromosphere Quark from SCS Astro, I'll do a review and post piccies when I get my hands on it. It looks a winner to me

The 4.3x Barlow I think is fine, hopefully around full disc with the right eyepiece and a short focal length refractor. I would ideally like to observe at a lower power than full disc as well, but really, I think this is a compromise well worth making given the spec and price. Imaging-wise, I can switch it between three different refractors to vary the focal length, and it should kick in nicely where my SolarMax 60 starts to run out of puff

Will it affect the pricing of the competition? I wonder if it already did with the Lunt 50...

Nice one, Luke. Will obviously be very keen to hear your thoughts once it arrives. Hopefully won't take you too long to receive it.

[Peter Drew]

I plead "guilty" to be at least one of the originators of the 50% dia of  the main objective for cost effective internal ERF sizes. This was based on experimenting with internal ERFs on a 220mm F12.5 refractor. At 75% of the focal length I found the ERF to get uncomfortably hot and had to employ a sizeable stand alone fan to cool it. At 50%  all seemed well and I was happy to recommend it. The experimental ERF was of the dyed in the mass type, the better Baader D-ERF reflects most of the heat out of the tube hence its "cool" designation. The internal ERF system allows the use of the relatively affordable Baader 75mm D-ERF for donor telescopes up to 150mm.    

[Joves]

With the size of its blocking filter (according to the specs), you would not quite get a full disk at 480mm focal length (450 mm max according to the flyer).

Thanks Michael.

I thought this might be the case, but thought they may have been suggesting a rough guide to focal length required for full disk viewing. I'd imagine at 480mm, it'd hopefully come close. I wonder, if the blocking filter is the limiting factor, would this mean you simply won't fit the entire disk into the FOV or that you will see the entire disk but not have all of it fall into its sweet spot showing even surface detail across the entire sun? Sorry if this is a naive question, by the way.

[michael.h.f.wilkinson]

Thanks Michael.

I thought this might be the case, but thought they may have been suggesting a rough guide to focal length required for full disk viewing. I'd imagine at 480mm, it'd hopefully come close. I wonder, if the blocking filter is the limiting factor, would this mean you simply won't fit the entire disk into the FOV or that you will see the entire disk but not have all of it fall into its sweet spot showing even surface detail across the entire sun? Sorry if this is a naive question, by the way.

I am not sure about this. It might be a situation like the LS35 with B400 blocking filter, which has a sweet spot, but does show the whole disk, or the cut-off might be fairly sharp. I think we need to await reports

[Joves]

I find the same with the PST, hence why I wondered. No problem getting the entire disk in the FOV, but detail varies across it.

Very true, guess we'll just have to wait and see. C'mon Luke, get a wriggle on!!

[Joves]

Looks like I may have just found a use for the Orion EON 110mm I bought a little while back which has seen almost no use. Being a 110mm APO doublet at f/6 with 660mm focal length, it strikes me that it would be almost perfect for this application. It has a rock-solid focuser on it and the fact that it apparently needs only the addition of a simple UV/IR block filter (which I already have by way of an Astronomik L filter) makes it seem like a very simple, but very appealing setup.

It only just occurred to me that I still have this scope, as it has been packed away since the NP127 took its place on the mount. Glad I didn't get rid of it, as I think it has just about sealed the deal on the Quark for me.

Getting kind of excited now