Optolong Hα 7 nm 2 "is a professional filter transmitting radiation from the Hα band, which is one of the three elements of the HSO palette.

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.

In order to further improve the parameters, the substrate was covered with a full multi-layer anti-reflection coating applied using ion implantation techniques. Thanks to this, the coatings are not only perfect in terms of optics, but also very durable and scratch-resistant.

The most important features of the Optolong Hα 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)
• efficiency of cutting out light pollution on the level> 99%
• scratch-resistant multi-layer anti-reflective coating

Technical specifications

• filter type: bandpass filter
• filter diameter: 2 "
• filter shape: round
• transmitted bands: Hα (656.3 nm)
• Half bandwidth: 7 nm
• maximum transmission: 80%
• 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%
• equivalent optical density for blocked lines: OD3
• Filter material: Schott optical glass
• type of coating: full multilayer coating (FMC)
• surface quality index: 60/40 (in accordance with the MIL-O-13830 standard)
• parallelism: 30 "
• RMS execution accuracy: λ / 4
• frame material: black anodised aluminum

Elements of the set

• Optolong Hα 7 nm 2 "filter

guarantee

24 months

/ Sample spectrum of narrowband filters (HA, S-II, O-III) /