Optolong SII Filter 2 inch

Optolong Filters SII Filter 2″ is a high quality narrowband filter that passes only the sulfur-II (SII) emission line around 672 nm. This makes the filter an essential part of a complete narrowband set (Ha, OIII and SII) for astrophotography. By almost completely blocking unwanted wavelengths and artificial light, the sky background becomes considerably darker and fine details in emission nebulae become more apparent.

The filter is particularly suitable for capturing emission nebulae such as the Crab Nebula, the Rosette Nebula and the Veil Nebula. In combination with H-alpha and OIII filters, classic Hubble palette recordings can be made (SII-Ha-OIII), showing nebular structures in color and detail.

The optical glass features multiple anti-reflective coatings, minimizing reflections and halos. The sturdy 2″ aluminum mount makes the filter compatible with filter wheels, 2″ adapters and astrophotography setups with large sensors. This provides maximum flexibility for both amateur and semi-professional astrophotography.

Observation goals
The Optolong SII filter is ideal for astrophotographers who want to capture emission nebulae in narrowband technique. It is mainly used with monochrome cameras and long exposure times, but can also be applied with modified DSLRs. For visual use, this filter is not suitable because the narrow bandwidth does not allow enough light through for the human eye.

Specifications

• Type: SII narrowband filter
• Wavelength: 672 nm (sulfur-II emission line)
• Diameter: 2″ mount
• Material: Optical glass with multiple anti-reflection coating
• Mount: Aluminum
• Application:
  • ✓ Astrophotography of emission nebulae
  • ✓ Narrowband images combined with Ha and OIII
  • ✓ Ideal for Hubble palette (SII-Ha-OIII)
  • ✗ Not suitable for visual use