This 2" Celestron ultra high contrast (UHC) light pollution filter blocks out most unwanted light pollution, making it easier to pick out faint nebulas from suburban and dark sky observing sites alike.
The 600 Ångstrom passband of this Celestron 2" ultra high contrast (UHC) light pollution filter provides improved contrast when compared with the wider 900 Ångstrom passband of the typical broadband filter. The filter has excellent transmission at the visually important emission lines of hydrogen-beta at 4861Å and doubly ionized oxygen at 4959Å and 5007Å. This combines with the narrow passband to make faint emission nebulas such as the Helix, Rosette, Veil, and North American stand out briskly against a dark sky. Brighter nebulas (such as the Omega, Dumbbell, Lagoon, etc.) stand out well under city lights. It can also be very useful in hunting down and enhancing very faint nebulas from a dark sky observing site.
The filter's advanced technology multilayer dielectric coatings let the filter achieve an outstanding transmission of over 97% across the entire passband, with a total blockage of the prominent light pollution lines. The 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. Ion beam hardened coatings provide excellent durability and resistance to scratching. The high transmission, sharp cutoffs, and more moderate 600 Ångstrom (60nm) passband of the UHC/LPR filter retains a more natural view, yet significantly boosts overall contrast. Imagers will appreciate the broader passband and inclusion of an extremely efficient 6563 Ångstrom H-Alpha passband. Comes in a protective clear plastic case. A ribbed rim makes it easy to thread in and remove the filter from an eyepiece in cold weather when wearing gloves.
