If you observe from highly light-polluted sites, or if you want the maximum contrast enhancement in observing faint emission nebulas from areas of moderate light pollution, an Orion UltraBlock telescope filter is for you. With an UltraBlock, emission and planetary nebulas are even visible from urban areas, where they are completely invisible without a filter! In darker-sky locations with only moderate light pollution, many objects will appear significantly enhanced over unfiltered and wideband filtered views.
Orion UltraBlock Telescope Filters block all forms of light pollution, including both narrowband mercury- and sodium-vapor lighting and broadband light pollution sources. UltraBlock Filters reject pollution from incandescent and fluorescent lighting, which wideband filters can't stop. Extremely high (99.9%) blocking of critical mercury and sodium emission bands and very high transmission of hydrogen-beta and ionized oxygen wavelengths result in the highest contrast gain of any competing light pollution filter.