H-Alpha 12nm CCD Filter - 50mm Round

The H-alpha 12nm CCD Filter is a narrow band filter for CCD photography that lets H-alpha light of emission nebulae pass while blocking nearly the whole remainder of the spectrum where the CCD is sensitive. The Full Width at Half-Maximum (FWHM) of 12nm is optimized for the use with common CCD cameras and allows the use of very fast optics. The filter is ideal for imaging hydrogen nebulae from both light-polluted and dark observation sites, significantly enhancing the contrast between objects emitting light at 656nm (H-alpha line) and the sky background. The filter completely filters out the emission lines from high- and low-pressure sodium and mercury-vapor lamps, as well as all lines of natural airglow and most of the distracting moonlight.