Askar H-Alpha 7 nm 2 "is a top class filter that transmits red light with a wavelength of 656.3 nm emitted by ionized hydrogen atoms, the registration of which is particularly important when photographing emission nebulae.

With an half-bandwidth of just 7 nm, this filter combines the ability to almost completely eliminate the undesirable component from sodium and mercury lamps with a high transmission for the Hα spectral line. , one of the most important from the point of view of astrophotography.

Attention! The Hα filter is not recommended for visual observations.

The most important features of the Askar H-Alpha 7 nm 2 "filter

• bandpass filter with maximum transmission for radiation with a wavelength of 656.3 nm
• very narrow half-width of the transmitted band (FWHM = 7 nm)
• OD4 equivalent optical density guaranteeing the effectiveness of cutting out light pollution at the level of 99.99%

Technical specifications

• filter type: bandpass filter
• filter diameter: 2 "
• filter thickness: 1.85 ± 0.1 mm
• filter shape: round
• transmitted bands: Hα (656.3 nm)
• location of the maximum permeability peak (CWL): 656.3 ± 1 nm
• Half bandwidth: 7 ± 1 nm
• maximum transmission:> 90%
• blocked bands: mercury lamps (435.8 nm, 546.1 nm, 577 nm, 578.1 nm), sodium lamps (598 nm, 589.6 nm, 615.4 nm, 616.1 nm)
• efficiency in blocking light pollution:> 99.99%
• equivalent optical density for blocked lines: OD4 (200 - 1050 nm)
• surface quality index: 60/40
• parallelism: 30 "
• light incidence angle: 0 - 8 °
• frame finish: matte black, anodized
• holder thread: M48x0.75

Elements of the set

• Askar H-Alpha 7 nm 2 "filter

guarantee

24 months