Antlia H-Alpha 1.25" 4.5 nm EDGE is a professional astrophotographic filter with a half-transmittance window width (FWHM) of 4.5 nm. It 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.

This filter combines the ability to almost completely eliminate the unwanted component coming from sodium and mercury lamps with high transmission for the Hα spectral line, one of the most important from the astrophotography point of view. It was made on a high-quality glass substrate, minimizing the risk of internal light reflections.

The Antlia H-Alpha 1.25" 4.5 nm EDGE filter is characterized by a steep slope of the permeability window and, unlike ordinary broadband filters, it does not show a significant decrease in transmittance resulting from the shift of the maximum of the permeability peak ( CWL). na successfully used in optical systems with a maximum light power of f/3.

Attention! The Ha filter is not recommended for visual or solar observations.

Highlights of the Antlia H-Alpha 1.25" 4.5 nm EDGE filter

• bandpass filter made on a high-quality optical substrate with maximum transmission for radiation with a wavelength of 656.3 nm
• compatible with astrographs with light intensity up to f/3 with minimal signal loss
• half bandwidth of transmission (FWHM) of 4.5 nm
• optical density equivalent OD5 guaranteeing high efficiency of light pollution removal

Technical parameters

• filter type: bandpass filter
• Filter diameter: 1.25"
• filter thickness: 2 ± 0.05 mm
• filter shape: round
• pass bands: Hα (656.3 nm)
• location of the peak of transmittance (CWL): 656.3
• half bandwidth (FWHM): 4.5 nm
• maximum transmission: >90% ± 1 nm from the maximum transmission peak
• blocked light pollution 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)
• optical density equivalent for blocked lines: OD5 (300 - 1000 nm)
• surface quality index (according to MIL-O-13830): 60/40
• parallelism: 30"
• manufacturing accuracy (RMS): λ/4
• holder thread: M28.5x0.6

Set elements

• Antlia H-Alpha 1.25" 4.5 nm EDGE filter

Guarantee

3-year manufacturer's warranty (for delamination of the filter and substrate)