Optolong Narrowband H-beta Filter 1.25" Mounted (OPT-H-BETA-125)
Opotlong narrowband H-beta filter is designed for nebula observation allowing 12nm 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 vapour, and both high and low pressure sodium vapour 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-coloured filter.
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.
Optolong H-Beta Spectrum and Characteristic
- Substrate: Optical glass
- Thickness: 1.85mm
- Tave: T>80%
- Blocking range: 400-700nm
- Blocking depth: light pollution line blocking >99%
- Surface quality: 60/40
- Transmitted Wavefront RMS: λ/4
- Parallelism: 30s
- Multi-layers anti-reflection coating
- Non-cementing optical substrate coating
- Optolong filter adopts precision coating based on 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.
What's in the Box
- Outer Box: silver box
- Plastic Box: PP material
- Lining: imported high pressure white EVA material