Baader Ultra-Narrowband 4.5nm OIII Filter
Choose: 1.25Choose: 31mm UnmountedChoose: 36mm UnmountedChoose: 2
Choose: 50.4mm Round UnmountedChoose: 50x50mm Square UnmountedChoose: 65x65mm Square Unmounted

Baader Ultra-Narrowband 4.5nm OIII Filter

£299.00✓ 2 year warranty


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About this product

Model:  baader_ultra_oiii_4.5nm_2
Part Number:  2458434W

Baader Ultra-Narrowband 4.5nm O-III Filters are precision grade filters for f/8 to f/3 optical systems.

Designed for imaging O-III emissions at an extremely narrow 4.5nm bandwidth. The enforced contrast results in much fainter stars providing more signal in the fainter nebula details, with the central wavelength of the filters being 502nm.

The manufacture of such ultra-narrow filters requires extreme coating homogeneity and very high center-wavelength (CWL) precision. Each filter is planeoptically polished and hard coated.

Filter sizes available:

  • 1.25"  (2mm glass thickness)
  • 31mm unmounted (2mm glass thickness)
  • 36mm unmounted (2mm glass thickness)
  • 2" mounted (2mm glass thickness)
  • 50.4mm round (3mm glass thickness)
  • 50x50mm square (3mm glass thickness)
  • 65x65mm square (3mm glass thickness)



Below is the real filter-spectrum, taken with an MPI-DADOS-Spectrograph. Comparision with the solar-spectrum (including solar absorption lines).


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