Optolong Night Sky H-alpha Filter 1.25" & 2"

The Optolong H Alpha Filter is a narrowband filter designed to isolate the Hydrogen Alpha emission line at 656.3 nm. It allows astrophotographers and visual observers to see deep red nebula structures with exceptional contrast, even in light polluted skies. By blocking almost all unwanted wavelengths, the filter reveals the pure glow of ionised hydrogen that makes up many of the most famous nebulae.
 
This filter is not only excellent for astrophotography but also valuable for visual observation through an eyepiece. When paired with a telescope and suitable eyepiece, the H Alpha filter enhances bright emission nebulae and helps you see structure that would normally be washed out by sky glow. It is available in 1.25 inch and 2 inch sizes, fitting a wide range of telescopes and visual setups.
 
Technical Features
• Center wavelength at 656.3 nm
• Narrow bandwidth around 7 nm for high contrast
• More than ninety percent transmission at peak
• More than ninety nine percent blocking of unwanted light from 300 to 1000 nm
• B270 optical glass for stability and clarity
• Multi layer coatings for reduced reflections
• Surface quality 60 to 40
• Wavefront RMS lambda by 4
• Parallelism 30 seconds
 
Performance and Compatibility
• Excellent for capturing fine hydrogen rich structures in nebulae
• Works with monochrome CMOS, colour CMOS, modified DSLR and mirrorless cameras
• Suitable for refractors, Newtonians, SCTs and astrographs
• Performs well in strong light pollution and under moonlight
• Can be used in an eyepiece for visual enhancement of bright emission nebulae
• Provides increased contrast when observing nebulae like the Lagoon, Eagle and Orion regions