One model, judged by its numbers
Lunt Solar Systems LS40THa B500
A small refractor built around an etalon that passes one wavelength of red light and nothing else. Prominences standing off the limb, filaments across the disc, and a Sun that changes by the hour. The most expensive 40 mm of aperture you will ever buy, and the one most likely to make you say something out loud.
What it shows, really
A solar instrument. It exists to show the Sun, so the night-sky views this page normally computes do not apply.
The numbers
| Aperture | 40 mm |
|---|---|
| Focal ratio | 400 mm · f/10.0 |
| Mount | Optical tube only — mounts on any photo tripod via a 1/4" thread — not included |
| Typical weight | 1.2 kg |
| Useful magnification | 7× to 80× at 40 mm |
| Resolution (Dawes) | 2.9″ — the tightest double star this aperture can split |
| Faintest star, suburban sky | around magnitude 9.3 |
| Observed price | €1290 seen 2026-08-22 |
Made for
The Sun · 5 out of 5
This is what the instrument exists for. Nothing else on this list comes close.
Taking it with me · 4 out of 5
One tube on a photo tripod. Solar observers take these on holiday.
Not made for
Learn my way around the sky · 0 out of 5
There is one object, and the instrument cannot see any other.
The Moon and the planets · 0 out of 5
Never. The etalon passes one wavelength of sunlight and blocks everything else, including the Moon.
Nebulae, clusters and galaxies, by eye · 0 out of 5
Never.
The family it belongs to: Dedicated hydrogen-alpha solar telescope
What it does well
- Prominences, filaments, plages and flares — the living Sun, not the flat disc white light shows
- Changes visibly over an afternoon, which nothing else in the sky does
- Small, light, and the target is up in daytime
What it costs you
- It shows the Sun. It shows nothing else, ever, at any price — there is no night-time use
- Tune-able etalons are a skill, and the view on a mistuned one is a disappointing red disc
- A 40 mm costs what a 250 mm Dobsonian costs. Be certain the Sun is what you want before this is what you buy
Worth knowing about this model
The current entry point to hydrogen-alpha since the Coronado PST went out of production. The B500 blocking filter suits visual use; imaging wants the B600 or larger. Needs a tripod you already own.
Prices are observed on the date shown, never live. Links marked paid link earn us a commission and cost you nothing extra.
Where to buy
- Astroshoppaid link€1290 seen 2026-08-23ships DE, FR, EU
- Amazon.frships FR
- First Light Opticsships GB
- Optique Unterlindenships FR
- Pierro Astroships FR
- Teleskop-Expressships DE, EU
1 of these 6 links earn us a commission, marked above. Sorted by price, never by what pays. How this site is funded.