Lumicon 2 Inch SCT Rear Cell Oxygen III Filter Teenage Mood Swings: How to Manage Teen Moodiness Averys House. Lumicon 2 Inch SCT Rear Cell Oxygen III Filter helps faint objects become much more visible against the blackened background of space. Lumicon 2 Inch SCT Rear Cell Oxygen III Filter Lumicon 2 Inch SCT Rear Cell Oxygen III Filter visually isolates the two doubly ionized oxygen lines (496 and 501nm lines) emitted by diffuse, planetary and extremely faint nebulae. The filter cell threads onto a Schmidt Cassegrain Telescope rear cell, and presents male SCT threads for accessory attachment. The filter cell allows ease of eyepiece changes without threading unthreading the filter, and is also easier to change out than the standard 2 filter cell with gloves on, for cold weather observing. Oxygen III Filter helps faint objects become much more visible against the blackened background of space and produces near photographic views of the Veil, Ring, Dumbbell and Orion nebula, among many other objects. This filter performs well under both light polluted and dark skies. Lumicon filters remain the worlds best and strictest quality control standards are employed throughout the production process. Each Lumicon Oxygen III Filter is individually inspected and scanned with the percentage of light transmittance of the OIII emission lines.