The 86mm UV/IR Cut H-Alpha Pass Pro Lens Filter from Kolari Vision cuts UV and IR light when your camera's native UV/IR filter isn't strong enough and lets some IR light pass through. It can also be used in combination with ND filters that do not cut out IR light. And it also works as a protective filter, as it causes no color cast nor exposure correction. This pro version features multicoated Schott B270 glass in a slim, knurled brass ring threaded on both sides. (The optional standard version has an aluminum ring.)
Alternatively, this filter can be used with a full spectrum modified camera to provide more than four times the sensitivity in the H-alpha (Ha) line compared to most cameras' native sensitivity, and greater than six times the sensitivity in the sulfur II line. A full spectrum modification entails manually removing the camera's low-pass filter and replacing it with a clear filter. (Kolari Vision can make the modification for you at a cost if you send in your camera to them.) This Ha filter has a similar transmission to Kolari's hot mirror filter, but with an expanded spectral response covering the H-alpha and sulfur II emission lines, making it also useful for astrophotography.