Solar Scope

[ThomasLondon]

Hi,

I currently have a Lunt 50THa and I am looking for something showing more detail and contrast on the sun's surface. I have been considering the new Meade SolarMax III 70 Double Stack, the Lunt 60 with DS (fairly expensive in comparison) and now stumbled across the Daystar Chromosphere. My key considerations:

- I love that I can just take out the Lunt at lunch time, put it on a photographic tripod, and I am up and running in about 5min. 

- When travelling, it would be easier to have one telescope to take with me for day and night use

- Cost is certainly an aspect - I do not want to spend more than about 3000 pounds.

May I get your input on a couple of assumptions I am making (and which may be completely wrong - sorry, I am not a telescope expert, I just love using them...)

- The only purpose of double stacking is to get a narrower bandwidth using (cheaper) filters with a wider bandwidth - by using two 0.7nm filters tuned to slightly different bandwidth the Lunt and the Coronado achieve 0.5nm effective transmission.

- A Daystar Chromosphere with a transmission of <= 0.5nm will hence show me the same detail as a Lunt or Coronado Double Stack with a single Etalon

- A refractor up to 80mm does not require an additional ERF

- A relatively cheap achromat will do - as I am only observing at a single wavelength, the correction for multiple wavelengths really does not make a difference (at least for H alpha)

So on that background I guess an 80mm refractor with the DayStar will give me a really good solution  am I right?

Best

Thomas

[Zakalwe]

16 minutes ago, ThomasLondon said:

- I love that I can just take out the Lunt at lunch time, put it on a photographic tripod, and I am up and running in about 5min. 

This requirement alone should make you think closely about a Quark....they take a good few minutes to warm up and come on-band (think 10 minutes). Any subsequent changes in the tuning will take a further 5 or so minutes for the temperature to stabilise. The Lunt system is totally different and, as you say, you can be up and running in minutes. Plus you can tune the etalon on the fly to look at different solar phenomena.

The views from the Quark are also very different. As there is a Barlow built in you are much more "zoomed in" than on the Lunt. This means that you are much more at the mercy of the seeing, both local and atmospheric.

[Zakalwe]

26 minutes ago, ThomasLondon said:

- The only purpose of double stacking is to get a narrower bandwidth using (cheaper) filters with a wider bandwidth - by using two 0.7nm filters tuned to slightly different bandwidth the Lunt and the Coronado achieve 0.5nm effective transmission.

- A Daystar Chromosphere with a transmission of <= 0.5nm will hence show me the same detail as a Lunt or Coronado Double Stack with a single Etalon

Double-stacking makes a massive difference. Maybe you should try DSing your Lunt50 first?
The second bit is not quite right due to the difference in the way that both systems work. Also. there have been very many reports of quality variances in the Quarks. I personally have had two and the imaging results were very very different between each.

26 minutes ago, ThomasLondon said:

- A refractor up to 80mm does not require an additional ERF

Correct. A 35Nm Baader H-Alpha filter makes an excellent internal ERF.....much better than a UV/IR filter.

 

26 minutes ago, ThomasLondon said:

- A relatively cheap achromat will do - as I am only observing at a single wavelength, the correction for multiple wavelengths really does not make a difference (at least for H alpha)

 

Not really. Cheap achros can suffer from spherical aberration which can affect the views/images.

 

 

This Lunt 60 was still for sale recently. it might be worth an enquiry?
The Lunt 60 etalon is tighter than the L50. Double-stacking that gives another level of detail altogether.

 

 

 

[Carbon Brush]

I recently went through similar thought processes.

In my case I had a standard PST and wanted something better.

Choices were improve the PST using a frac, buy a quark, or solarmax, or Lunt.

Carving up a perfectly good frac to mod the PST felt wrong, and seemed like a lot of messing around.

At the end of the day I walked away from Daystar because of historic poor reviews and an absence of recent good reviews.
There was a nagging doubt in my mind that if I got poor performance from a genuinely poor quark, it might be blamed on my refractor,ERF, etc.

While thinking Lunt vs Coronado I came across a couple of used LS60 models on sale.
Having seen lots of good reports of the scopes and Lunt's after sales support, the choice was clearly going to be Lunt.

That left only the choice of objective diameter, blocking filter size, etalon tuning method and focusser.

I decided for myself that in UK skies, the 60mm or 80mm objective was adequate.
The number of days when the extra magnification available from an 80mm upwards lens being small.

From reports by others, I thought a focus upgrade of some sort would be needed to handle a big eyepiece or camera.
The 12mm blocking filter was considered worthwhile over the 6mm.
Double stack was also reported to boost detail. Though an expensive upgrade.

At the end of the day I had almost bought a low spend (if there is such a thing) on a 60mm with standard focus, tilt tune, single stack.

Then another came up locally. Much higher spec and a much bigger hit on the wallet.
60mm again, 12mm BF, pressure tune with pump, feathertouch focus and a 60mm double stack.
So I went for it convincing myself that by buying locally I had saved on petrol and did not need to eat much for a few months.

Having the standard and feathertouch focussers to hand (it came with both) I can see why this upgrade is highly recommended.
As for everything else, I have not had enough sunny days to be able to usefully comment.
I reckon pressure tuning from the pump will be a big help on high magnification viewing but I would not have been persuaded to buy new.
Etalon tuning without grabbing hold of the scope has to be a good thing.

If you make a few searches around SGL there is a lot of discussion solar scope choices. Be prepared for information overload!

Keep asking and searching. Good luck.

David.

 

[vlaiv]

I'll offer my view on few points:

28 minutes ago, ThomasLondon said:

- The only purpose of double stacking is to get a narrower bandwidth using (cheaper) filters with a wider bandwidth - by using two 0.7nm filters tuned to slightly different bandwidth the Lunt and the Coronado achieve 0.5nm effective transmission.

It's not about cheaper filters - it's about filter design and finesse - double stacking provides more contrast because it provides more finesse. This is related to FWHM and "sharpness" of filter curve - you want it both narrow and also not being wide at the bottom (and letting continuum light in which reduces contrast).

29 minutes ago, ThomasLondon said:

- A Daystar Chromosphere with a transmission of <= 0.5nm will hence show me the same detail as a Lunt or Coronado Double Stack with a single Etalon

Not really, refer to upper point. Daystar Chromosphere does not have guaranteed precision in filter band pass / finesse. In general, from what I've seen it falls between single and double stacked by offered contrast.

32 minutes ago, ThomasLondon said:

- A refractor up to 80mm does not require an additional ERF

Depends on filter design - best to adhere to manufacturer instructions. Daystar for example does not require it up to 80 or 100mm (can't remember which one exactly - best to consult manual), but does suggest IR/UV cut filter or Halpha interference filter.

33 minutes ago, ThomasLondon said:

- A relatively cheap achromat will do - as I am only observing at a single wavelength, the correction for multiple wavelengths really does not make a difference (at least for H alpha)

In theory yes, but in practice much will depend on figure of lens. Most regular achromats are fine tuned for green light (the least SA at around 500-550nm). In red part of spectrum you can have various aberrations that will degrade views, like spherical, astigmatism or such.

 

[Carbon Brush]

The Lunt scope identified in the earlier post is the scope that I almost bought.

I would have bought it, and had arranged to view. But the higher spec scope came up locally.

David.

[ThomasLondon]

Thanks for all your inputs!

Well, I understand the time for heating up - but that's a topic even for professional etalons. I think I could live with that. 

Looks like I need to think about this a bit...

Best

Thomas

[Davey-T]

The main thing that separates the choice is having looked through a few Lunt LS60 they all give pretty much similar views, having looked through a few Quarks they give very variable views.

If buying a second hand Quark I'd want to see images taken with it, if buying a new Quark be prepared to return it if you're not happy with the results.

Dave

[Zakalwe]

On 03/02/2019 at 19:13, ThomasLondon said:

Thanks for all your inputs!

Well, I understand the time for heating up - but that's a topic even for professional etalons. I think I could live with that. 

 

Don't underestimate this. I find the wait between tweaking the tuning a complete pain in the whatsits, especially whilst imaging. The Lunt is a heck of a lot easier to use.