Optolong H-Beta FWHM 25nm Filter 2" (50mm). HBETA25NM2
The broadband H-beta filter is designed for nebula observation. It allows a 25nm bandwidth of light with a central wavelength (CWL) of 486nm. It reduces the transmission of certain wavelengths of light, specifically those produced by artificial light. These wavelengths include mercury vapor, both high and low pressure sodium vapor lights, and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow). H-beta emits a light wavelength of 486nm and it is a blue-colored filter. Main Use and Performance • Use with a large aperture telescope under clear and dark viewing conditions. • Suitable for viewing on the faint and elusive Horsehead Nebula and California Nebula. • Narrow-band filters do not eliminate the effects of light pollution or increase the object’s brightness. In many cases, they increase the contrast between nebula and the night sky, but do not brighten the nebula. • WARNING: Optolong filters are not designed for sun observation. DO NOT LOOK AT THE SUN WITH AN OPTOLONG FILTER. BLINDNESS could occur if you fail to observe this warning.