Optolong OIII 6.5nm unmounted filter 36 mm

Optolong OIII 6.5nm unmounted filter 36 mm

DESCRIPTION
The Optolong OIII 6.5 nm unmounted filter (36 mm) is designed for narrowband imaging of emission nebulae in the oxygen III emission lines at 495.9 nm and 500.7 nm. It transmits a narrow 6.5 nm band centered at 500 nm, while efficiently blocking unwanted wavelengths from artificial lights (mercury and sodium vapor) and natural skyglow caused by atmospheric oxygen.

This filter is ideal for use under strong light pollution or during full moon. It increases contrast between nebulae and the background sky. It is commonly used together with H-alpha and SII filters to produce SHO images (Hubble palette), such as those of the Pillars of Creation (M16).

The non-cemented optical substrate is coated using ion-assisted deposition technology. This ensures high resistance to scratching, thermal stability (no shift in central wavelength), and excellent passband transmission. The planetary rotation coating system guarantees uniform coating thickness and precise spectral performance.

TECHNICAL SHEET

• Manufacturer: Optolong

• Filter type: Narrowband interference OIII

• Bandwidth: 6.5 nm

• Central wavelength (CWL): 500 nm

• Emission lines: OIII 495.9 nm and 500.7 nm

• Format: 36 mm round, unmounted

• Application: CCD/CMOS narrowband imaging

• Transmission: High at passband, high optical density off-band

• Coating:

  • Multi-layer anti-reflective

  • Ion-assisted deposition

  • Non-cemented optical substrate

  • Thermally stable

• Intended use:

  • Planetary nebulae

  • Supernova remnants

  • SHO imaging under moonlight or light pollution

• SHO compatibility: Yes (with H-alpha 7 nm and SII 6.5 nm filters)