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Ha filters
For solar Ha you need a special filter which only allows the light from the emmission wavelength of Hydrogen (6562.8 Angstrom) to get through.
These filters are VERY sensitive and expensive. The bandwidth of available filters can vary from 1A to the "best" at about 0.5A.
Lumicon make a prominance filter (1.2A) which can be used on scopes up to 100mm aperture ( But I'd still recommend using an energy rejection filter (ERF) up front), Coronado do a range of SolarMax filters starting at 40mm aperture up to 90mm. Daystar also have very good filters but these require a power source to heat and stabilise the bandwidth. Lunt have also started to sell solar filters and scopes. The cheapest is probably the Coronado PST, which is a 40mm scope fitted with a 0.7A etalon filter.
The "normal" Ha filters used for deep sky observering are not suitable for Ha solar work. The minimum bandwidth is usually 7nm (70A)
The cost of entry is pretty high. An 80mm ERF filter would cost about $300+, a PST about $600. The SM40 starts about $1200, SM60 $4000 etc
Observing the Sun can be dangerous, don't be tempted to use inappropriate filters.
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