1.25'' Telescope Filter H-Beta 25nm fit Horsehead Nebula in Dark Sky observation For Sale
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1.25'' Telescope Filter H-Beta 25nm fit Horsehead Nebula in Dark Sky observation:
H-Beta 25nm Filter allows you to visually observe the ever-popular yet elusive Horsehead Nebula with large aperture telescopes under dark skies, and can also be used to image the Horsehead as well as others that emit light at 486nm, such as the California and Cocoon nebulae.
- CNC machined and black anodized aero-metal filter cell that is ultra-thin to provide largest clear aperture
- Laser-engraved to prevent fading
- Multiple layers of anti-reflection non-cementing coatings applied via electron-beam gun evaporation with Ion-assisted deposition
- Filter substrate is fine-optically polished to 1/4 wave and <30 parallelism over both surfaces
- High value transmission of pass-band and optical density of off-band is assured through Optolong's planetary rotation system, a homogenous and precise coating procedure
- Each filter comes with a plastic case with high pressure EVA case lining
- Best used with a moderate to large aperture telescope and clear, dark skies
WARNING: The filters are not designed for sun observation. DO NOT LOOK AT THE SUN WITH this FILTER. You would be BLIND if you fail to observe the warning.