Learning to use a Solar Scope with an H alpha filter

[sophiecentaur]

TL;DR

I just bought a second hand Coronado PST and I want to be sure whether it's actually working.

I just bought a Coronado and, typically, there are no sunspots to look at. If there were, then I could compare what I see in that dim dark red image with what my basic Baader shiny filter delivers. I understand that there's a learning process involved and I imagine all first-time users have had my experience of Coronado.
Do any of you have experience and opinions on this please? I was wondering whether my DSLR could help here.

 

[davenn]

Summary:: I just bought a second hand Coronado PST and I want to be sure whether it's actually working.

Wooohooo

...... I just bought a Coronado and, typically, there are no sunspots to look at. If there were, then I could compare what I see in that dim dark red image with what my basic Baader shiny filter delivers. I understand that there's a learning process involved and I imagine all first-time users have had my experience of Coronado. Do any of you have experience and opinions on this please?

The PST is a good scope many of them in use around the world

Yes you have to get used to that darked red image, some of the other makes like my LUNT do have an image that's a bit brighter
mainly because of the larger aperture they have ... my LUNT is 60mm compared to your PST at 40mm.

Looking at the time of your post, I did my daily Ha image save around that time. here's what was visible around that time ...damn, the image won't upload ... don't know what is wrong with the forum ? it's well below maximum size, in pixels and kb
dopey system

ummm how can I do this... OK put it up on my own www site see if you can see this ...

http://www.sydneystormcity.com/200122_0955UT_Ha_GONGsm.jpg
there is one spike prominence visible at about 1 o'clock and an active region upper central area

no actual spots visiblecheers
Dave

 

[sophiecentaur]

@davenn thanks for that image. I wouldn't expect to have seen anything of that! I looked at a daily image on a solar weather website and there was so much detail (taken with very expensive gear, no doubt) and with loads of processing that I felt highly inadequate for not having spotted at least some of the details.
One question that you could perhaps answer and that is how fussy would the etalon tuning be in order to see that flare? I was so unconfident about having set the ring right that I could hardly believe I was going to see anything but a whacking great sunspot - which my cheapo Baader filter shows clearly. Thing is, the PST was an eBay purchase and I would like to be able to make a dispute if the filter is not working.

Are there any tests that I could make, other than looking at the Sun? I doubt it. I can try my trusty DSLR when I take delivery of my 1.25 inch T mount.

 

[davenn]

I wouldn't expect to have seen anything of that! I looked at a daily image on a solar weather website and there was so much detail

Spaceweather.com ? if so that isn't a Ha image, it's visible light and the one much further down the page is different again
for showing coronal holes

and with loads of processing that I felt highly inadequate for not having spotted at least some of the details.

There would have been no processing on that image I posted, they are raw out of the scope and update every couple of minutes or so.

You shoud be able to make out that prominence on the edge and maybe a start to pick out that small active region

One question that you could perhaps answer and that is how fussy would the etalon tuning be in order to see that flare?

Tuning, isn't an issue, focussing and position in the field of view will make the difference.
I googled the PST and couldn't see any info on it's tuning range that is, it's a 1.0 angstrom scope is there actually a know labelled tuning ?

I can try my trusty DSLR when I take delivery of my 1.25 inch T mount.

yup, it would be good to see what you get

 

[PAllen]

This might be helpful:

http://astronomyonline.org/aoblog/aoblog32.asp
https://blogs.msmvps.com/mickyj/blog/category/hobbies/astrophotography/

 

[sophiecentaur]

This might be helpful:

Thanks for that. Yet again I note that most of the images that people post are presented with have an Orange Colour. There is even a mention in one of those links about the picture looking orange. H alpha is deep red, of course, and someone with a new PST and very little knowledge could be very confused by the fact that what they see is nothing like the publicity. There is a parallel thread which discusses low cost microscopes and telescopes and how the images are always disappointing and inferior and that many Christmas presents end up being used once and then put in a cupboard. PST, even though it's the cheapest way in, is still hundreds of GBP yet I think many of them may be 'failing' first time users because of the visibility problem. More info is needed from adverts and 'instructions', I think. Issues that seasoned Astrophotographers tend to take for granted.

Also I am planning to use my DSLR but back focus is sure to be a problem. I have ordered a s/h barlow lens to try to avoid this problem (and to make up for the small 400mm objective image on the sensor). I also have a ZWO entry level camera which may end up as the best solution, despite the relatively low res sensor.

 

[davenn]

Yet again I note that most of the images that people post are presented with have an Orange Colour

true, a bit if image processing there

there are a couple of red coloured images down the page of that second article that are much closer to what you should see

I also have a ZWO entry level camera which may end up as the best solution, despite the relatively low res sensor.

which model ?
I would be using it rather than the DSLR which the weight of will put a lot of stress on the end of the PST

 

[davenn]

OHHH and a nice sunspot group has grown over the last couple of days, best one for some time
If I get a clear sky today, I mite fire up the LUNT solar scope

 

[sophiecentaur]

If I get a clear sky today,

Lol.
The ZWO is an AS120MC and I take your point about loading with a DSLR. I guess the 1.2Mp sensor can deal with any details on the Sun's surface. I'm not trying to resolve binary stars with it on the PST. It's just a nuisance to have to take the laptop out in the garden too.

 

[davenn]

ZWO is an AS120MC

A good ZWO camera ... have a couple of solar astro mates that use it
It's a much better camera than you give it credit for so did you look at the nice sunspot over the weekend ?

 

[sophiecentaur]

so did you look at the nice sunspot over the weekend ?

Cloud after the Sun rose over the trees, I'm afraid. I can wait . . . . .

I wonder about the sensitivity of that camera though. I tried PHD for guiding but it was never convincing. I must get it sorted though and the Sun is bright enough, even through that Etalon filter.

 

[davenn]

I wonder about the sensitivity of that camera though.

Some examples from the mono version of the ZWO 120mm

I had 2 more but the flamin forum is refusing to upload them
really getting frustrated with this

 

[davenn]

OK try again

The solar images are with a 60mm Coronado solar scope
The lunar shot is with a Meade LX200 scope

Juan is from SE Spain, his solar imaging is truly outstanding. You should see some of his images
they look almost 3D. He puts a lot of work into those style doing video clips and staking in Registax
and some other processing

 

[sophiecentaur]

Lovely images. Meanwhile the sunrise was brilliant today with a lovely blue sky again. At the same time that the Sun rose over the trees to our east, clouds came rolling in from the west to meet them. Grrrr.
I'll get that pesky pigeon if its the last thing I do!.

 

[sophiecentaur]

Bright sun early this morning. I got the PST out and, by the time the Sun was high enough to see, there was some high level haze. That makes focussing very hard because you cannot tell when it's optimal (or even at all). No sigh of any sunspot but I am sure I saw a couple of flares which moved with the sun, unlike all the other shash which moved with the scope.
I saw distinct low level clouds drifting over the Sun at about midday (fairly sharp so I guess my focus was ok). I will try again tomorrow.

Life is never simple, though.
NEQ6 does a great job of following the Sun for me but that loopy mount arrangement allows no change of focusser angle as the scope makes its Equatorial journey. I am making myself some 50mm rings so I can rotate the scope to my preference. I am making them out of aluminium plate and I am having great fun making up some hinges, using Lumiweld, which is basically an aluminium solder / brazing alloy. That stuff is really good and, although I wouldn't make a bicycle frame with it, it wets both ally surfaces and forms a very convincing join. I think I am getting to be a better metal worker than astronomer!

 

[AndyG]

The PST is a wonderful little scope that will serve you well. The image should be bright enough to see clearly and sharply and prominences/flares around the edges of the image should be easy to spot but be aware that they are usually small! Tuning will bring these in and out of view.
A word from the wise. If the image is really dim, I mean dark enough that makes the prominences hard to see, the scope may have a problem. There is a long standing issue with Coronado scopes that results in one of the filters degrading -"the ITF rust issue". As it degrades the image will get dimmer. If your image is really dark, this may be a useful discussion of the actual problem and possible solutions. However, if the image you have is clearly visible and you are happy with it, carry on and enjoy the view!

 

[sophiecentaur]

If your image is really dark, this may be a useful discussion of the actual problem and possible solutions.

Thanks for that. Interesting. I wouldn't say that the image is really too dark and not too different from what I saw in a working pst, once. I will try to grab a really clear day and look at the Sun when there's no doubt about what I should be expecting. Also, I can dig out my shiny Baader filter and see what I can see on my ED80 S/W scope as a comparison.

 

[davenn]

No sigh of any sunspot but I am sure I saw a couple of flares which moved with the sun, unlike all the other shash which moved with the scope.

hmmm, tho not a huge spot, it should have stood out like a sore toe.
Hi Andy
Welcome to PF
I'm assuming you own a PST ? If so, nice to have another solar astronomer on board
You may be interested in my "pinned" thread
https://www.physicsforums.com/threads/solar-imaging-and-techniques.925656/

A word from the wise. If the image is really dim, I mean dark enough that makes the prominences hard to see, the scope may have a problem. There is a long standing issue with Coronado scopes that results in one of the filters degrading -"the ITF rust issue". As it degrades the image will get dimmer. If your image is really dark, this may be a useful discussion of the actual problem and possible solutions.

Good info
Dave

 

[AndyG]

No, I don't currently own a PST but my Ha goto is a little Solarmax 40mm with a Leica zoom eyepiece (ridiculously expensive but excellent for solar work) on a lightweight alt/az mount. Also run a Baader Herschel wedge on an SW ED80 (or Altair ED102 or SW 127 ) generally on a much bigger push-to dual-head alt/az. Then there's the Baader film filters and various other bits that I've got to find time to play with! Have done quite a few formal outreach viewing sessions over the years too, some impromptu sidewalk sessions and more formal lectures.

 

[davenn]

No, I don't currently own a PST but my Ha goto is a little Solarmax 40mm with a Leica zoom eyepiece (ridiculously expensive but excellent for solar work) on a lightweight alt/az mount.

cool, if you do any solar imaging, please post them in that other thread I linked to

my toys ...

The one mostly used the LUNT LS60THa on a HEQ5 PRO mount

and the occasionally used system
A DAYSTAR Chromo Ha system on a Skywatcher ED120mm and the HEQ5 PRO mount

Dave

 

[AndyG]

How do you rate the Daystar against the Lunt?

 

[davenn]

How do you rate the Daystar against the Lunt?

Two very different ways of getting same/similar results

LUNT ( which ever model/size), very easy to use. An all in one system

Daystar, 2 models available, the prominence filter and the chromospheric filter
I bought the chromo. one as the bandwidth of my LUNT is a little broader ( 0.7A +- 0.2 A (approx)
That is more suitable from prominence viewing.
The Daystar Chromo. is approx 0.25 - 0.5 A centred on approx 0.4 A. This is better for viewing
surface features.

My Daystar Chromo Quark unit as you see above on the 120mm refractor also can be ordered
with adaptors to suit Canon or Nikon cameras and lenses ( Canon for me).

I have to admit that my LUNT gets much more use than the Daystar, mainly because of the ease of use.
All the photos in my main pinned solar observing thread, that I linked to earlier, have been done
with the LUNTcheers
Dave