A solar telescope is an instrument built to look at one object, and it shows that object in a way nothing else does. Where a white light filter gives you a clean white disc with sunspots on it, a hydrogen alpha telescope gives you prominences standing off the edge and a surface that looks like fire.
What hydrogen alpha isolates
Hot hydrogen emits strongly at a wavelength of 656 nanometres, deep in the red. A solar telescope for this line passes a band a fraction of a nanometre wide around it and rejects everything else, which is an enormously harder job than cutting brightness. The result is that you see the chromosphere, the layer above the visible surface, where prominences and filaments live, instead of the photosphere below it.
Why the price sits where it does
The cheapest dedicated hydrogen alpha instrument in this index prints $995.00 for 40mm of aperture. That is more than three times the price of a 130mm dobsonian, for a tenth of the light grasp, and the money is not in the objective at all: it is in the etalon, the blocking filter and the tuning mechanism that hold that narrow band. Aperture is almost irrelevant to what such an instrument costs.
Who it is actually for
It is a second or third instrument for almost everybody who owns one, because it does nothing at night. Its case is that it works in daylight from a city balcony, needs no dark sky, no travel and no late night, and shows something that changes visibly over an afternoon. For people whose observing time is daytime, that is the whole argument.
Questions people ask about telescope
What is a solar telescope?
An instrument built to observe the sun, usually by isolating the hydrogen alpha line at 656 nanometres so that prominences and chromospheric detail are visible.
Is a solar telescope better than a filter?
It shows different things. A white light filter shows sunspots on the photosphere and costs a fraction as much; a hydrogen alpha telescope shows prominences and surface texture that no white light filter can reveal.
How much does a solar telescope cost?
The cheapest dedicated one in this index prints $995.00 for a 40mm instrument, quoted from the maker's own product page.