Celestron 94123 1.25-Inch UHC/LPR Filter (Black)Our 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. In addition to it's optimum spectral and optical characteristics, the UHC/LPR filter offers important features that set it apart and result in the highest quality celestial views: The multi-layer dielectric coatings are plasma assisted and Ionbeam hardened using the latest technology for durability and resistance to scratching. Improved transmission translates to maximum image brightness and contrast. Users of smaller, 4"-11" telescopes will especially appreciate the high efficiency, and larger scope users will love the rich star fields and detailed subtle nebular shadings that are left intact. The high transmission, sharp cutoffs, and more moderate 60nm passband of the UHC/LPR filter retains a more natural view, yet significantly boosts overall contrast. Imagers will appreciate the broader bandpass and inclusion of an extremely efficient H-Alpha passband (656nm).Celestron 93623 Narrowband Oxygen III 1.25 FilterThe 1-1/4" OIII narrowband filter isolates just the two doubly-ionized oxygen lines (496 and 501nm lines) emitted by planetary and emission nebulae, while blocking the rest of the overall spectrum of light. The result is extreme contrast between the black sky background and the faint photons of OIII light needed for detailed views of the Veil, Ring, Dumbbell, Crescent and Orion nebulae, among other objects. Each filter has an ultra hard, vacuum-deposited coating carefully designed to block all of the visual spectrum ranging from 400 to 700 nm This eliminates the un-natural colored halos surrounding bright stars common with O III filters of less sophisticated coating technology.