The IDAS HEUIB-II (H-alpha Enhanced UV IRBlocking) filter is designed for enhanced spectrum DSLR's and one-shot color CCD astronomical cameras.
Besides removing the IR and UV ends of the spectrum which are often out of focus in refractive optics, it isolates the common H-alpha line relative to the surrounding extreme red end of the spectrum, making it easy to bring out the faint H-alpha emission nebulosity of astronomical photos, yet retain the background color balance of broadband photos.
