realistically, how much detail can you observe visually in H-alpha with 60mm of aperture?

[Florin Andrei]

I always appreciate how much I learn from these impromptu discussions. This is great, it's like I'm back in school again. @Rusted and @astro_al could you please point me at some good material regarding the usage of small Coronado-like etalons with larger apertures? What are the limitations?

I will do my best to try and build an H-alpha stack around my 200mm SCT, if I can - in the long run. Well, at least I will see how close I can get to that. There are many, many hurdles to clear on that path (the price and scarcity of full aperture ERFs for example).

One unknown is seeing - but I live in a place where seeing at night tends to be pretty good (no jet stream, near an ocean, etc). I guess daytime seeing should follow similar patterns (maybe overall not as good due to the extra thermal energy).

[Merlin66]

Florin,

Drop me an email and I'll send you the PST mod document.

Unfortunately nowadays the costs of all the necessary components is getting costly.

I use a SM60 double stack on my ED80. Works well for me.

 

[Rusted]

You can have a readymade H-alpha SCT, or build one with an ERF from Airies Ukraine.
Airies Tri-band ERF prices match at Baader's largest D-ERF but climb on upwards as expected with increasing aperture.

An internal, sub-aperture D-ERF from Baader will work with a cheap achromatic refractor and PST etalon but has drawbacks and risks at larger apertures.
Starting with a secondhand 150 f/8 [or 120mm f/10] and a slightly smaller internal D-ERF, you can enjoy large scale H-alpha images and imaging with due care.

Monochromatic light [H-alpha] is kinder to achromatic optics than white light.
DIY [ATM] is a [potentially] cheaper route to larger apertures than buying off-the-shelf H-alpha scopes.
You just have to be very aware of the potential dangers of focusing that much heat!

There is lots of information online about building and using H-a telescopes if you search for it.
A whole bundle of steadily advancing knowledge and imagery from the world's experts at "Solar Chat" forum.
Running ideas past them is a sure way to avoid pointless expense, starting a fire or instant blindness!
 

[Florin Andrei]

@Rusted - you nailed it. Aries ERF + 200mm SCT is the long-term goal. It should also be able to work in the calcium band. Also - replace the ERF with Baader solar film and you have a great machine for white light imaging. There will be hurdles on the way to that goal, I'm sure, mostly related to the ERF availability and price. We'll see.

I'm not afraid of DIY and designing/building systems from scratch. I've a degree in Physics, I've built a dobsonian from scratch (including the mirror), I've built a mirror grinding machine, and now I'm working on a second, larger mirror for a bigger dobsonian. Future plans include even larger, more complex systems, perhaps a corrected Dall-Kirkham hybrid, for which I made a few blueprints in OSLO.

I need to figure out what is the practical limit, in terms of diameter, for custom ERFs. A compact, lightweight cDK could do double duty as hydrogen/calcium imager during the day, and DSO imager during the night. But that's for much later, if it will happen at all.

Okay, enough daydreaming, I'm back to the salt mines.

[Rusted]

Your ambitions match my own of over half a century ago.
Be careful what you wish for!  I built some white elephants but had a lot of fun.

The usual arbiter applies to all [solar] work as aperture increases: SEEING, SEEING and SEEING.

If I could have the better seeing conditions, which I so rarely enjoy, I could be a far better imager.
I overcome my limitations by imaging at literally every opportunity which presents itself. [I am retired.]
Practice, practice, practice! Plus always being in the observatory when seeing conditions might just improve.

The working conditions and equipment with which I image are constantly analysed for potential improvements.
I cannot afford specialised, narrowband filters so I make the most of what I have.

Since I use a PST etalon I am limited to f/10 optics. I choose to us a specialised 6" f/10 for H-alpha close-ups.
Whole disk imaging is well covered by others with years of practice, expertise and far better equipment.

I saw an opening in close-ups as a very late comer to H-a solar imaging. So now I specialise.
The money I spend is concentrated on the goal. Instead of being scattered right across the entire field.
It took me a very long time to learn that simple lesson.

Increased aperture = increased focal length = increased magnification = much narrower field of view AND ever greater demand on seeing conditions.

Not all owners of solar SCTs are able to enjoy the potential benefits for increased resolution because of their average seeing conditions.
Those who do manage to pull it off, repeatedly astonish us with their images. You may be luckier but it is still a very difficult path.

Good luck.

[Merlin66]

Yeah,

Seeing is King!!

I find down here on the Bellarine that my SM60 and ED80 give me as good as I can get with the average seeing conditions.

Like many solar imagers I dream of a >100mm aperture but in all honestly I’d have to relocate to take advantage of it. I’m not sure my wife would agree!!?

[Florin Andrei]

Problem solved.

Looks like the unit had some issue, maybe it was damaged in shipping, who knows. Anyway, DayStar fixed it under warranty.

Now I see granulation all over the disk, a small spot on one side surrounded by bright areas, a long thin dark line in the middle of the disc, and various prominences around the edge, of all shapes. It's at low activity, so there aren't that many big features, but the filter definitely works. The background is very dark.

Thanks everyone for your help!