Celestron's 1-1/4" Light Pollution Reduction (LPR) Filters are designed to selectively reduce the transmission of certain wavelengths of light, specifically those produced by artificial light. This includes mercury vapor, and both high and low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. sky glow).
The new ultra high contrast (UHC) LPR filter has improved contrast over the typical broadband filters. Sky background is darker, and contrast of emission nebulae are noticeably improved. The advanced technology coatings enable the filter to achieve an outstanding transmission of over 97% across the entire bandpass, with total blockage of prominent light pollution lines. The perfect filter for viewing nebula from light polluted skies, or for boosting the contrast of nebula from dark sky sites.