Narrowband OIII 18nm Light Pollution Filter - Ideal for Nebula Observation

The Optolong narrowband OIII filter is designed for nebula observation allowing 18nm bandwidth of light centered on a wavelength of 500nm through, which corresponds to OIII emission lines, /*C*and*C*/ reducing the transmission of certain wavelengths of light, specifically those produced by artificial light including mercury vapour, /*C*and*C*/ both high and low pressure sodium vapour lights /*C*and*C*/ the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow).

OIII emits 495.9nm /*C*and*C*/ 500.7nm /*C*and*C*/ it is a blue-green coloured filter. Many images of planetary nebula /*C*and*C*/ supernova remnants are taken only with H-alpha /*C*and*C*/ OIII filters. They show great structural details, but have natural colours, looking /*C*like*C*/ an RGB image.

Warning - Optolong filters are /*C*not*C*/ designed to be used for solar observation. Do /*C*not*C*/ look at the sun through this filter as it will cause permanent eye damage.

FEATURES

• 90% transmission at major OIII line 495.9nm /*C*and*C*/ 500.7nm.
• 0.1% transmission of off-band, specifically the major emission lines of artificial light pollution (i.e. Na 589nm, Hg 435nm /*C*and*C*/ 578nm)
• Suitable for visual observations on most emission nebulae, planetary nebulae /*C*and*C*/ supernova remnants
• 1.25' /*C*or*C*/ 2' Mounted Sizes.
• Supplied in a protective plastic case with EVA foam lining
• 2mm (1.25' / 2') Thick Schott Glass
• Fine-optically polished on both sides - ensures accurate λ/4 wavefront /*C*and*C*/ <30 seconds parallelism over the both surfaces
  
  

  Please note - this graph is for the older generation which had a 25nm bandwidth. This updated 18nm version has a tighter bandpass area.

  Red Line - Represents the transmission curve of the OIII Filter.

  Green Line - The Major Emission Lines of Nebulae: H-α (656.3nm), H-β (486.1nm), OIII (495.9nm) /*C*and*C*/ OIII (500.7nm)

  Orange Line - The Major Emission Lines of Artificial Light Pollution: Hg / Mercury (435.8nm, 546.1nm, 577nm /*C*and*C*/ 578.1nm), Na / Sodium (598nm, 589.6nm, 615.4nm /*C*and*C*/ 616.1nm)