H-Beta 12nm (Broadband Filter) 2”

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 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.

Technical Data

• Schott substrate material
• Thickness 2.0mm
• Surface Quality: 60/40 (Refer to MIL-O-13830)
• Fine-optically polished to ensure accurate 1/4 wavefront and <30 seconds parallelism over the both surfaces
• 90% transmission at H-beta line 486nm
• 0.1% transmission of off-band, specifically the major emission lines of artificial light pollution (i.e. Na 589nm, Hg 435nm and 578nm). Transmission of 0.1% is equivalent to OD3(Optical Density), and a high optical density value indicates very low transmission, and low optical density indicates high transmission.

Coating Parameter

• 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

Filter Cell

• Ultra-thin filter cell minimize vignetting by maximize possible clear aperture
• Aerometal Material | Precise CNC Machining | Sand Blasting Process | Black Anodized Finish | Extinction Treatment to Prevent Reflection | Laser Engraving No Fading

Package

• Plastic PP Case | Imported High Pressure EVA Case Lining | Silver Cardboard Box | High Density Sponge Carton Lining

Spectral Curve

• The Major Emission Lines of Nebulae
• H-β486.1nm OIII 495.9nm OIII 500.7nm H-α656.3nm
• The Major Emission Lines of Artificial Light Pollution
• Hg 435.8nm 546.1nm 577nm 578.1nm
• Na 598nm 589.6nm 615.4nm 616.1nm

OPTOLONG astronomical filters launched since 1990s, OPTOLONG become China’s first astronomical filter manufacturers, with independent R&D ability, has successfully developed more than 20 popular astronomical filters so far.Since OPTOLONG astronomical filters launched, with its high cost performance and good after-sales service OPTOLONG astronomical filter received the recognition from customers and agents both at home and abroad.OPTOLONG astronomical filter has been cognition by fans all over the world, you are welcome to join our local agent.

OPTOLONG astronomy filters advantages

Optical performance: high precision wavelength, high transmittance, deep cutoff, good surface finish, no pinhole
Adopt precision optical double-sided polishing technology (< 30 “)
Halo is restrained effectively, good flatness (RMS λ / 4 or less)
Good substrate material, use German schott glass and fused silica glass
Aircraft aluminum ring by CNC machining, anodic oxidation treatment
Safety packaging, PP plastic box + PVC sponge + cartons