OPTOLONG 2″ Filter H-Beta 25nm Astronomy Monocular Telescope Enhance Contrast of Nebulae for Visual Observation
Narrowband H-beta filter is designed for nebula observation allowing 25nm bandwidth of light centered on a wavelength of 486nm through, and reducing the transmission of certain wavelengths of light, specifically those produced by artificial light including mercury vapor, and both high and low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow). H-beta emits 486nm and it is a blue-colored filter.
Main Use and Performance:
- Use with a large aperture telescope under clear and dark viewing conditions with good seeing
- Suitable for viewing on the faint and elusive Horsehead Nebula and California Nebula
- Narrowband filter do not eliminate the effects of light pollution or increase the object's brightness. In many cases, they increase the contrast between nebula and night sky, not brightening the nebula.
- WARNING: The filters of Optolong are not designed for sun observation. DO NOT LOOK AT THE SUN WITH OPTOLONG FILTER. You would be BLIND if you fail to observe the warning.
- Multi-layers anti-reflection coating
- Non-cementing optical substrate coating
- Electron-beam gun evaporation with Ion-assisted deposition coating technology for durability and resistance to scratching, as well as stability on CWL(central wavelength) no deviation affected by temperature change
- Planetary rotation system offers precision and homogeneity of coatings ensuring high value on transmission of pass-band and Optical density of off-band
- Ultra-thin filter cell minimize vignetting by maximize possible clear aperture (clear aperture is 45 mm )
- Aerometal Material | Precise CNC Machining | Sand Blasting Process | Black Anodized Finish | Extinction Treatment to Prevent Reflection | Laser Engraving No Fading
- 2″ OPTOLONG H-Beta 25nm Filter