Posted 31 January 2013 - 02:08 AM
OK, the specs sheet shows a filter bandwidth (Full Width at Half Maximum) of about 397 angstroms which is a little too broad to make a good narrow-band nebula filter. It also shows a peak transmission of 100% which might be stretching believability a little, as most quality production interference filters with this kind of bandwidth rarely have peak transmissions much higher than 97%. It is a "compromise" filter with a bandwidth between that of a broad-band LPR filter and a narrow-band nebula filter. In short, it is a "jack of all trades, master of none" when it comes to a filter for deep-sky objects. It will dim continuum objects like star clusters and galaxies more than the broad-band LPR filters do. It would work on emission nebulae to some degree, but won't quite provide as much of a contrast boost as a true narrow-band nebula filter like the DGM Optics NPB, Orion Ultrablock, or the Lumicon UHC filter (the "true" UHC filter). If you want a good nebula filter, I would recommend the DGM NPB, Orion Ultrablock, or Lumicon UHC as better alternatives. Clear skies to you.