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Mark-V

Double stack etalon -is it worth it ?

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Is it worth getting a double stack etalon for a solar scope for viewing the sun or is the visual gain not worth the additional cost ?

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It depends a lot on what sort of performance you want. Double stacking enhanses the contrast considerably at the cost of a much dimmer image calling for a cover over the head to enjoy satisfactorily visually. DS is very good for imaging, particularly for full solar disc images. I prefer the larger high resolution single stack aperture the same amount of outlay will provide. YMMV.  :icon_biggrin:

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Hi, Mark. I think Peter has hit the nail on the head.

I’m visual only and enjoy the extra ‘teasing out’ of detail that the DS set-up affords. The difficulty in answering your question is that your take on ‘worth the additional cost’ can only be subjective ... and you can only know once you’ve tried it!

Any way you can arrange a test view somehow? Perhaps at a shop (the outlay for the etalon justifies any trip) or do you know anyone or any club that might help?

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Hi Mark, whereabouts are you roughly ? I'm in NW Kent, just.

You're welcome to have a look through my LS60DS on a sunny day, it tends to reduce the brightness drastically so the higher the Sun the better so it does give a "better" view but entails more fiddling around tuning.

Dave

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Good answers above. I'm a double stack junkie because I love the extra surface detail, but as Peter said you can get great results from larger single stack ha scopes - or external ha filters on traditional scopes - particularly if you like to view prominences, which benefit less from double stacking. The advice to try before you buy is particularly apt for solar observing, because it can get very expensive. 

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I agree also with Peter.  I would buy the biggest single stack I prefer the single 80 over the double 60 and cost is the same pretty much same 

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I disagree to an extent as in my experience the lower the bandwidth and etalon / s with the greater finesse have offered

me the best and most interesting views (again quality over ....... ) I’ve been using a DS SM11 60 for a season now and it displays a surprisingly bright 

DS image the reason being is that the set up only utilises 1 ERF (on the external stack) , whilst my DS PST uses 2 ERFs 

and the image given the aperture is a lot darker but having said that the etalon finesse appears to be superior.

Anyway to answer your question I definately do think it’s worth trying a DS.

 

Brian 

 

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I've a smaller aperture Lunt 50mm, and I took the plunge to DS: well worth it to me - the detail on the disc is amazing, even during these solar minimum times.

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Mark,

Firstly, I dont want to get into one of these "my setup is best so lets write something to make me fell good about what I spent on all this kit".

The first thing is you need to state what solar scope you own? Then we can offer a targeted response to whether double stacking will offer a "better" visual view.

As stated above double stacking does dim the image (this is a disadvantage) - if your scope has small aperture and the image is already dim then this may push you over the edge. If you decide to add a front etalon that is not full aperture such as adding a front 50mm to a 60mm scope then this is also going to cut your brightness by an increased amount.

To the question "will I see more" then it is a fact that a double etalon changes the bandpass and allows more to be seen.

My history in solar:

I started with a single stack tilt tune LS60 (in 2013 when the sun was active on the surface) and liked the view but wanted to see more surface detail (detail that I could turn the focuser and actually see in sharp focus).

I sold that scope.

Next I purchased a double stack pressure tuned LS60 (with DS60 front etalon) as a "matched" pair from Lunt. The view was beyond compare to what the single stack LS60 could provide. The sheer amount of features available to be seen on the solar surface was increased many fold. I was able to tune the scope and focus in sharply on these features. Sure the image was slightly darker but it never bothered me in any way.

Now I am binoviewing the DS60 setup which has further dimmed the image but not to my dissactisfaction and the view IMHO is better than one eye with the same scope.

Finaly, I added a "rotator" and discovered that rotating the front etalon also allows more solar features to come in and out of view. This would be impossible in a single stack scope.

I have absolutely no intention of selling this solar scope and love the views it has given me over the 4 years that I have owned it. I would not go back to single stack and find it odd that anyone says they would (but thats my humble opinion and I am entitled to it!).

I have never tried an LS80 so whether thats better or not I cannot say. But I did plenty of research on DEDICATED solar forums before I spent £1000s and the opinion there was that double stack "shows more stuff".

I suggest that you tell us what solar scope you have (if you have one) and that you seek out these dedicated solar forums where you will quickly be able to search out 100s of posts of people asking the same question and read the responses they received but do take some responses with a "pinch of salt". Solar is an expensive hobby and unfortunately there are too many people wanting to convince themselves they spent wisely and bought the best kit or state opinions after having spent 5 minutes looking through someone elses scope  :( (not referring to anyone above in this comment but its a fact).

Finally, bear in mind that the sun is not doing much in Ha at the moment (compared to solar max in 2014) so what you are going to see is pretty thin gruel on offer. You may be better getting a good single stack scope and planning to add a full aperture double stack later when the solar cycle increases (may be a few years yet :( )

If you don't own a scope then second hand bargains do come up but most second hand scopes are for sale "over priced" so consider carefully before jumping on one of them.

HTH,

Alan

Edited by alanjgreen
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I have the Lunt 75 external filter which I double stack and as Alan rightly points out you do see more double stacked but my Lunt 75 mounted on my Tak 100 or my Lunt 80 in-single binoviewed is also breath taking when there is much HA going on double stack is great hard  to justify 2k pluss extra though if I'm honest I'd say a Lunt 60mm front etalon on a nice Ed scope is better than a Lunt 60 and two is well very expensive but even better I would try to see double stack for yourself first somebody local may help if you can before spending over 2k then you will know what your getting for your extra outlay 

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Ultimately aperture and double stacking do different things. Increasing your aperture adds resolution, whilst adding a double stack will increase contrast.

Increasing the resolution will allow you to see finer detail, contrast will make it easier to see the detail that is there.

I have used a PST 40, a Quark in a variety of scopes up to 150mm and now have a 100mm PST Mod. All of them single stack. Cost is probably the single reason I haven’t gone to double stack, if I did I would want probably 70 or 80mm aperture and I can’t afford that! A 100mm PST Mod gives wonderful views and doesn’t cost ‘000s but they are not necessarily the easiest things to to put together yourself.

The best Ha scope I ever looked through was a double stack SolarMax 90mm. Amazing proms, amazing resolution and amazing contrast. Amazing price too ;)

I hesitate to say, but until you know what floats your boat, it is hard to give a definitive answer. I enjoy proms in Ha more than I do surface detail so DS is less of an attraction. You could easily and rightly counter argue that to say that I might prefer surface detail if I had a DS scope!!

You certainly don’t ‘need’ to tell us what you have got already, but it would be helpful if you did put some more context on the question so you get better answers.

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I bought a PST in 2005 initially to view an Annular eclipse followed by a Total eclipse a year later. I was very happy with my PST which I felt covered my needs. About 15 months ago I borrowed a Double Stack, at a star party, which screwed into the front of the PST. The difference it made was amazing IMHO.

Several months later a S/H DS came up on the SGL classifieds (£400) - I bought it and over the last year I have had some very enjoyable views of the solar surface. I do compare the standard PST with the DS in place from time to time and it confirms that I am glad that I bought the DS.

I agree that it does dim the view but I put a cover over my head which works brilliantly.

pst.jpg

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Going by images alone what floats my boat most I think are prominences. Spots are black blobs. Surface detail is fascinating just to realise what it is, but prominences are drama!

So given the expense of equipment, I personally would go for what gives the best visual prominence results, and enjoy what quality that gives to other features. 

Given the above, any recommendations?

 

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I viewed the Venus transit in the USA in 2012 through one of these scopes - https://www.365astronomy.com/Lunt-LS152THa-B1800-152mm-H-Alpha-Telescope-Feather-Touch-Focuser-Pressure-Tuner.html

The owner had Dentmeier binoviewers and TeleVue EPs (can't remember which one) - so if money is no object there you go.

However, I really want to keep the thread on line and I don't believe Mark-V is thinking about this sort of expenditure.

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Mark you can replicate a similar view for less than 2k (new) using a Quark , 2” 35nm and an ST152 , I know that I do 🌞

well the odd time that the seeings up to it 😬

 

In my experience you can’t really get to the bottom of what your really after until you try a set up for yourself , you can read 

all you wish but they’re usually filled with reviews by Lunt newbs , I’ve owned and tried numerous Lunts since 

their inception in 2007 / 8 and I’m afraid that I still do not rate them , so in summary it’s best if you can try before you buy.

 

Brian 

 

 

 

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1 hour ago, Solar B said:

Mark you can replicate a similar view for less than 2k (new) using a Quark , 2” 35nm and an ST152 , I know that I do 🌞

well the odd time that the seeings up to it 😬

 

In my experience you can’t really get to the bottom of what your really after until you try a set up for yourself , you can read 

all you wish but they’re usually filled with reviews by Lunt newbs , I’ve owned and tried numerous Lunts since 

their inception in 2007 / 8 and I’m afraid that I still do not rate them , so in summary it’s best if you can try before you buy.

 

Brian 

 

 

 

Perhaps Stephen Ramsden reviews may help over on the solar Chat forum I don't think he's a Newbie reviewer 

And I'm the opposite to you Brian I've owned several Solarmax II including two double stacked versions and the views were good but in my opinion not as good as the Lunt scopes I've owned but I would say the solarmax II double stack version is great value for money also the solarmax II has two etalon one internal one external so best advice is as always try and see what's best for you but it can be costly 

Edited by garryblueboy

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It’s all very subjective Garry and perhaps I’ve clarified the reason why your DS SMll 60 views were so bright , 

the Lunt 60s offer the same set up with one internal and one external etalon  , however the SMIIIs offer the superior configuration of 2 externally stacked etalons.

For the ultimate “Air Spaced” HA  views one can look no further than the Isle of Man Solarscope etalons !

I do respect Stephens reviews but I’ve actually been using HA scopes a little longer than he , and as always 

there is no substitute for trying the real thing.

 

Brian

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1 minute ago, Solar B said:

It’s all very subjective Garry and perhaps I’ve clarified the reason why your DS SMll 60 views were so bright , 

the Lunt 60s offer the same set up with one internal and one external etalon  , however the SMIIIs offer the superior configuration of 2 externally stacked etalons.

For the ultimate “Air Spaced” HA  views one can look no further than the Isle of Man Solarscope etalons !

I do respect Stephens reviews but I’ve actually been using HA scopes a little longer than he , and as always 

there is no substitute for trying the real thing.

 

Brian

Agreed Brian on the solarscope from Isle of Man we are fortunate to have what we both see as an ideal setup I don't think I mentioned my solarmax views being bright though in fact my Lunt are far brighter but that also is due to the 75mm external etalon fitted to the Lunt 80 and when it was fitted to the Lunt 60mm and it was far better than the 50 double I had and so on hopefully one day I will have the pleasure of a 100mm solarscope filter from Isle of Man  Or Coranado or Lunt 

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Having looked through Helen’s IOM solarscope, I would definitely put one of those at the top of my wanted Ha list, amazing views.

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Talking about LS152s I see that ones back up for grabs on Astro Buy & Sell 😎

My apologies Garry , I’m sure you eluded somewhere some time ago about how bright your SM 60DS image was 

and I’m always striving toward the ideal set up , looking out for something new and affordable to try but I do have 

nearing the ideal mount situation as having a pier outside does save a lot on set up times.

Hows about SGL have a Solar event , that would be great for trying various weather permitting 👍

 

Brian 

 

Edited by Solar B
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13 hours ago, Solar B said:

Talking about LS152s I see that ones back up for grabs on Astro Buy & Sell 😎

My apologies Garry , I’m sure you eluded somewhere some time ago about how bright your SM 60DS image was 

and I’m always striving toward the ideal set up , looking out for something new and affordable to try but I do have 

nearing the ideal mount situation as having a pier outside does save a lot on set up times.

Hows about SGL have a Solar event , that would be great for trying various weather permitting 👍

 

Brian 

 

I fear Brian that owning the LS152  may be like most large scopes on the ideal day it will blow your socks off but I read our skies will not do it justice I did ponder when it came up for sale first time I'm quite impressed so far with the LS 80 binoviews are the best I've seen since starting solar 5 years ago , know what you mean with the mount I've tried many over the years along with all types of OTA I think I'm almost there with present scopes and mounts also .

A SGL Solar day would be great also give members a chance to see different set ups ☀️

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Thanks for all the advice . I have a solar max II 90 at the moment and may financially in a position to double stack it in the next few months which is why I was asking

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It's debateable as to whether a double-stack enhances prominences over a single-stack. Some say that a DS has a dimming effect on proms. 

I have a LS50F stacked to a PST. The details in solar flares are definitely better with this arrangement.

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Why not put a wanted ad out for a used SM90 .... I reckon the best ones were gen 1 & USA made and used to cost a small

fortune !!! but they do exhibit real finesse , so you needn’t necessarily require an SMII one , but I’d also recommend collecting 

such as you really don’t want one de-contacting while in transit.

 

Brian 

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