The IDAS HEUIB-II (H-alpha Enhanced UV IR Blocking) filter is designed for enhanced spectrum DSLR's and one-shot colour 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 colour balance of broadband photos.
The comparison shots shown below were taken with an enhanced Canon 6DH using a standard Canon UV/IR blocking filter and an IDAS HEUIB-II filter. These show a clear difference both in the background sky colour balance and the contrast of H-alpha nebulosity in the extremely faint object IC1396. Note the good background colour balance as shown in the histograms of the individual colour channels of the HEUIB-II filtered image.
Canon 6DH with standard Canon UV/IR blocking filter:
Canon 6DH with IDAS HEUIB-II filter: