The Wideband StarGuy H Alpha,
FWHM 12nm, filter is a deep red long pass filter that enhances the contrast of
nebulae emissions and reduces the effects of light pollution by only passing
the hydrogen alpha light. The H Alpha filter is designed to transmit a wide
band of Hydrogen allowing more light through than the narrowband version for
shorter exposures. Ideal for emission nebulae such as the Horsehead and North
American. The filter eliminates halo effects with double sided polishing
technique and coatings. 100% tested and inspected by MrStarguy.