Celestron UHC (Ultra High Contrast) Light Pollution Reduction 48mm Filter (Fits 2" Eyepieces)

LPR (light pollution reduction) filters are designed to selectively reduce transmission of certain wavelengths of light, specifically those produced by artificial light.  These include mercury vapor, high & low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emissions in our atmosphere.  The UHC LPR filter has improved contrast over the typical broadband filters, giving darker background skies and noticeably improved contrast of emission nebulae.  The advanced coatings enable and impressive 97% total transmission across the entire bandpass, with total blockage of prominent light pollution lines.  It is a perfect filter for viewing nebula from light polluted skies as well as for boosting the contrast of nebula from dark sky sites.