solar telescopes

[lesbehrens]

hi. my interest in solar observing has increased. (I've seen the light :lol:). i am looking at buying a solar telescope of my own and well i have a few q's.
when i use my astro clubs PST i only saw solar proms and sun spots. i was wondering i u can see filaments and flares with that type of scope?
can u only use Coronado's eyepieces to magnify the sun more with a Coronado scope? mine didn't get a good focus.
if i got a bigger aperture scope will i see more proms etc or just get a more detailed view of the sun?.i have looked at the Coronado web site and looked at the images taken through other scopes. the PST showed proms, spots, filaments. is this only seen when u photograph the sun? or the time i had the PST none were about on the sun? (i know the sun has been quiet).

Are there any other tips u could give me on my adventure?

thanks
les:astron::sunny:

[sheeny]

G'Day Les,

You should be able to see spots, proms, filaments, etc. You should be able to see the "orange peel" on the surface of the sun.:thumbsup:

I found that it took me a while to learn to focus the PST well. It also takes a while to train you eye to view the Ha image in the scope. There's not a lot of contrast there with a standard PST.

I read where someone wrote in a thread here that they didn't reckon double stacking a PST was worth it. I found the new price of the SM40 filter a bit steep, but I recently picked up a second hand one through IT from Rob Greaves and I must say, thanks to a few tips from Rob, that it has made a significant improvement to my PST:thumbsup:. Much more contrast, so achieving focus is easier and there's more detail to see.

You are not limited to Coronado EPs. My 13mm Nagler works a treat, but I do have a set of Cemax EPs now that I mostly use with the PST.

A bigger aperture, I would imagine, would give you the opportunity to go to higher magnifications and more resolution (if seeing permits it). The only Ha scope I've used is the PST, so if anyone with more solar experience can correct me there pease do so!:P

Al.

[rat156]

Hi Les,

I have the SM40 scope, which is essentially a slightly better PST. The main things that are better are the focussing and the T-Max tuner. I have played with a PST before and found that the focussing mechanism was not to my liking. Also if you plan to image through it the SM40 is a better investment as it's much easier to set up. Larger aperture will allow higher magnification, but seeing will limit that most days, so I wouldn't go over 60mm.

I can see, and have imaged the following phenomena using the SM40;
Sunspot (well there's only been one visible since I bought the scope)
Active regions
Prominences

Keep an eye out on the secondhand market, I found mine on Astromart back when the dollar was pretty close to parity, so it was cheap compared to Aus. Watch out for secondhand PST's, a lot have the so-called "rust" problem, I'd inspect before buying, which really counts out the US.

[lesbehrens]

so a PST vs SM not much difference? do u really have to train your eye to see the surface detail? getting a scope with higher angstrom will let u see more?
les

[rat156]

Hi Les,

There is a difference, the SM40 is definitely better, but not by much. The main problems I've seen with the PST is that it's hard to get all of the solar disk in focus at once. The SM40 is much better in that regard. Other than that and a few design differences, they are both 40mm about 0.7A Solar scopes, so the views are similar.

Less bandpass (lower A) gives more contrast, hence more detail. There is a tradeoff though, as you lower the bandpass, you get less light through, so dimmer picture. What you want is a scope with <0.5A bandpass for surface effects (sunspots etc), but one with a wider bandpass for flares and prominences. That's why doublestacking can work very well.

Cheers
Stuart (about to go and look for a possible sunspot forming)

[lesbehrens]

so the double stacked option is the way to go?? if u just got a telescope with a <0.5A would be suited to more surface detail as it will limit the brightness of the surface. and the <0.8A is better for the proms as it allows som more light in to see them?
so if i got this Lunt 60mm Ha Double Stack Telescope (B600) it would be a very good choice? compaird to this Coronado SolarMax 40 Telescope <0.5A .
les

[lesbehrens]

i also notice that there are scopes with different lens type. eg Lunt 60mm Ha Telescope (B1200) / (B600) is that correct?how does this make my viewing better?
les

[lesbehrens]

i also have something else to add. i i bought a Coronado solar telescope do the come doubled stacked? or do we need to buy a another filter?
les

[rat156]

I believe that this refers to the diameter of the blocking filter (usually in the diagonal), so that would be 12 and 6 mm respectively. This means that you have a slightly larger FOV as this works as a field stop. With the 40mm scope and a 5mm blocking filter I have no problems getting the whole disk of the sun in the FOV with an 18mm eyepiece. At 60mm (not sure what the focal length of the Lunt scope is) with all other things being equal I think I'd struggle, but 6mm sounds about right. Maybe someone else who has a larger blocking filter can comment.

I would think that the Lunt and Coronado scopes should be pretty similar in performance.

Cheers
Stuart

[rat156]

I would think that there would be a significant price difference between a double stacked 60mm scope and a single 40mm scope. If you can afford the aperture and extra filter, then go for it, but at least compare the Solarmax60 with the Lunt 60. Also be careful of the manufacturers claims as to bandpass, the view through both 60mm scopes with one etalon in place would be similar, the view doublestacked would also be similar. I think the Lunt scopes should be much cheaper as they have an ongoing sale on to try and establish themselves in the market, could represent good value ATM, but I haven't seen too many pics taken through one...

Cheers
Stuart

[rat156]

Like the Lunt you can get them either double stacked or not, depends on how much you're prepared to pay for it. Apparently it's better to get them double stacked at the factory as the match the two etalons to give you a better result.

Cheers
Stuart

[lesbehrens]

i just have find someone who has a Coronado up here up from the PST. so i can see a diff. between them. i don know weather to buy a lunt or not since no one has got one yet to report about it.
if there is anyone close to kilcoy and has a better solar scope than the PST would u let me have a look???
what your view?? buy a lunt or Coronado?
les

[lesbehrens]

how do the daystar telescope compare?
les

[Merlin66]

Maybe I can share my experiences with solar telescopes.
I got "hooked" in 2007 and finally bought a PST ( the initial one I found suffered from "rust"; so did the second!)
A great starting point; surface detail and proms visible, easy to use.
The 0.7A bandwidth did a good job, but the "sweet" spot the small 5mm blocking filter ( BF5) and some astigmatism from the pentaprism limits it.

(The diameter of the suns image is about 1/100 the focal length ie for a 600mm fl the primary image is about 6mm diameter)

Then bought a SM40/ T max/ BF10 filter set up. This was fitted to my ED80 and the views both in contrast and detail was a major improvement on the PST. The longer focal length and larger BF allowed some excellent views.
Double stacking the SM40 on the PST showed what 0.5A bandwidth could do!! The granulations and active areas stood out like never before!! This is what it's all about!
With the narrower band width, I found I had to re-tune the SM40 to follow the proms and different setting would show different detail... fascinating!
I then upgraded from a webcam to the DMK21 mono and "invested" in a BF10 filter ( 10mm aperture) this is where the fun REALLY started. Wide views of the solar surface with the SM40 and detail with the SM40/PST.
But obviously you want more......
I went across to the "dark side" and modded the PST. This gave me a taste of what a larger aperture could achieve. Still some issues with the "sweet" spot, but once again a major improvement. Even had the SM40 double stacked on the modded PST.... I enjoyed the opportunity to get the practise imaging and observing in Ha...
The chance came to buy a SM60/BF15 filter.... I went for it.
The images in the ED80 were once again phenomenal; no sweet spot, large clear, high contrast views of the surface and proms. The ultimate!!
Or so I thought.... I was made an offer I couldn't refuse for the modded PST and almost immediately a similar offer for the SM40; would you credit it along came a chance at a SolarMax60 scope ( this is the Coronado scope version of the SM60 /BF15 filter mounted in a sexy 500mm scope) I went for it!!! It's due to arrive later this month; so I'll be able to double stack with the SM60 and put the filters back on the ED80 if needed.

Quite a journey for me. But being able to get such wonderfull views of the sun is something else again. It's alive, and every day shows something different.
The Lunt scopes are pretty good value, but remember they do not have full aperture etalons like the SM60... they use a 60mm objective infront of a small (PST sized) etalon and a range of blocking filters to suit the focal length. The double stack adds a front etalon ( similar to the SM60, hence the price!) Other than that you can't "upgrade" unless you take the Modded route. So to me there's no comparison between the base SM60 and the Lunt 60; the SM60 wins hands down.
Also this concern about "matching" the double stack etalon... if they are built correctly and function well as a separate filter there's no technical reason why they would not work as a double stack. The get the 0.5A bandwidth each filter has to be tuned just off the Ha and it's the overlap that gives the improved resolution ( albeit with reduced light throughput)
Sorry to go on....
Hope it helps.

[lesbehrens]

thanks. it's good to hear about some else's experience.
so All in all do u think the SM60 is the better buy to the lunt 60mm as the lunt is like the pst in summery?
les

[Merlin66]

I've hadn't had the chance to test the Lunt, but I can say the SM60 system is first class and will provide images and visual views that will keep you very, very happy for a (hopefully!) a long time.
It has a large enough aperture to give good resolution minimal "sweet" spot effects and can be used with x4 barlow for imaging!
BTW the Lumicon prom Ha filter and Daystar etc are also very good; they need an ERF up front and will only work in beams f20 and above. This is usually achieved by stopping down the aperture to achieve the f20 ie a 50mm ERF on a 1000mm fl scope. ( without a barlow! - must be either a f20 beam in a refractor or a SCT)

[lesbehrens]

hi i have found out that there are rust problems that ha occured. once fixed will they get this problem again?. why does this rust problem occur?
les

[Merlin66]

On the early PST builds the energy rejection filter coating (ERF) used on the objective (Gold coloured) suffered break down in sunlight/ heat build up. As the coatings started to deteriorate they looked as if they were covered with a coating of brown "rust". (BTW this was not due to Ha light!)
Coronado/ Meade replaced the objective ( under warranty) with one which had a general broadband coating ( Blue colour). This new coating is 100% stable and doesn't deteriorate. At the same time they re-located the ERF to a smaller filter just infront of the blocking filter in the eyepiece holder.
You CANNOT just replace the "rust" objective without adding a safety filter in the optical path.
Hope this helps.

[lesbehrens]

oh.
so do u think this would happen a again even thow the lens has been replaced?
les

[Merlin66]

No, is the answer. The new blue coating doesn't have any real energy rejection component to break down; it's just like a normal telescope objective. I don't know of anyone having any problems with the "Blue" PST's.

[lesbehrens]

great thats good.
over the double stacked PST vs a SM 40 what would u choose?
les

[Merlin66]

Both have merits!
The double stacked sm40/PST gives improved resolution (0.5A), but is still limited by the focal length ( 400mm) and construction of the PST ( the use of the penta prism). Remember that the SM40 filter used to double stack is the same as the one in the SM40 stand alone system.

The only difference is the addition of a sparate blocking filter built into a diagonal. These BF's can have larger apertures which gives wider fields for viewing and can be used on longer focal length scopes.
So, the SM40/BF10 type arrangement can be used on almost any refractor up to say 1200mm fl, and gives cleaner images; the PST is always ( unless you start doing mods) limited to the 400mm fl and the constraints of a BF5 filter.
Hope this helps.

[lesbehrens]

thank you for your help.
les:P

[lesbehrens]

one last question. how well can u see filaments so the surface of the sun with a PST?are they very distinctive or is it a skill to see them?
thanks
les