Optolong 3 nm H-Alpha Ultra - Narrow band filter for astrophotography - Shooting with extreme contrast even with strong light pollution.

• 2" mounted with filter mount
• Suitable for telescopes and lenses with focal ratios of f/3 and lower
  Blackened edges to avoid internal reflections
• Extremely narrow bandwidth of only 3 nm for maximum contrast
• Central wavelength 656 nm