Optolong OIII Filter 3nm 2 inch

Optolong Filters OIII 3nm 2″ is a professional narrowband filter that passes only the OIII emission line around 500.7 nm with a bandwidth of only 3 nm. This makes it one of the most selective filters in its class, ideal for advanced astrophotographers who want to capture emission nebulae in maximum sharpness and contrast.

The extremely narrow pass-through effectively suppresses virtually all interfering light from sodium and mercury lamps, as well as moonlight. The result is a dark sky background and an exceptionally high signal-to-noise ratio. Nebulae such as the Veil Nebula, Helix Nebula and planetary nebulae come into focus with unparalleled detail and texture.

The filter is made of high-quality optical glass and features multiple anti-reflection coatings, minimizing reflections and halos. The robust 2″ aluminum mount makes it suitable for use in filter wheels and 2″ adapters. Thanks to the high transmission of the OIII line, this filter is ideally suited for long exposure times and stacking, achieving impressive results even under highly light-polluted conditions.

Observation goals
This filter is intended for serious astrophotographers who want to capture emission nebulae in their purest form. It works optimally with monochrome cameras, possibly with a complete narrow-band set (Ha, OIII, SII). For color cameras the effect is more limited, but still usable. Not suitable for visual use, as the extremely narrow bandwidth allows too little light to pass through for the eye.

Specifications

• Type: OIII narrowband filter
• Bandwidth: 3 nm around 500.7 nm
• Diameter: 2″ mount
• Material: Optical glass with multiple anti-reflection coating
• Mount: Aluminum
• Application:
  • ✓ Astrophotography of emission nebulae
  • ✓ Very high contrasts under heavy light pollution and moonlight
  • ✓ Ideal for use with monochrome cameras
  • ✗ Not suitable for visual use