Aperture is where your resolution comes from, as you know. Seeing is worse in the day time, so it's not as easy to use large apertures unless your seeing supports it commonly. That said, the sun is close compared to other stars, and it's simply amazing what you can resolve on our star with a mere 60mm aperture. More aperture will give you more resolution. But, larger aperture comes with massive price increases. 40mm to 60mm seems to be fairly affordable. But going to 80mm is a huge step in cost. And going larger than that is a massive, massive increase in cost. Worth it? Well, that's a personal thing. I've had the pleasure of viewing at 40mm and 150mm apertures in HA and the views from the larger aperture under good seeing is simply amazing. There's no substitute for aperture. If your budget allows, I would definitely target the 80~90mm aperture range, if it's an option. It will be price. But if this is an option it will be well worth it if you want to watch 8 minute old light that moves before your very eyes.
Quality build is important, and details are important, such as a good focuser and the ability to upgrade parts and/or add a double-stack option.
There are options that are modular that you simply add to a current scope you already have, such as front and/or rear mounted etalons and blocking filters. There are dedicated solar scopes and there are modular accessories that turn an existing scope into a HA scope. So there are several options.
So depending on your budget, I would point you towards the Solarmax III series, either the 70mm double stack or the 90mm double stack, if it's within budget. Good blocking filters, good focusers, and great apertures with a double stacked etalon, ready to go. Well made scopes. Alternatively, a Lunt 80mm if you can afford it, with a double-stack module if able, and go for the larger blocking filters (10mm~15mm). Alternatively if you can find Solarmax 90mm front mounted etalons you can put one on an existing scope. And then there are options like Daystar Quantum series or Solar Spectrum Observer series for rear mounted etalons on an existing scope.
It would help to know what your top budget is.
And really, I would suggest you find a way to look through a HA scope soon so you can get an idea of what it's like and see what your expectations vs reality are.
That said, when I view through my 150mm aperture solar scope with my binoviewers, the view is very much like the images I made, and I can see crazy amounts of detail and structures in high resolution. It's truly fantastic and blows night-sky viewing away (at least for me) seeing a living star in such resolution with unique 8 minute old light, all day every day.
Right now we're approaching the peak of the solar minimum of cycle 24, so there's not a lot of crazy activity going on (huge spots, flares, big features daily, etc). So I find full disc viewing isn't particularly breath taking (though still amazing to see and I like to view it as a full disc every day I can for a moment at least just to scan the surface and limb for structures to look at with my bigger scope). I much prefer simply looking at a specific large structure at high resolution, such as a huge prominence or an active region, etc with a large aperture and a pair of binoviewers, it's just nuts what you see.
Edited by MalVeauX, 28 January 2019 - 06:49 PM.