Product description
Description:
The 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 nebulae.
Features:
1.CNC machined and black anodized aero-metal filter cell that is ultra-thin to provide largest clear aperture
2.Laser-engraved to prevent fading
3.Multiple layers of anti-reflection non-cementing coatings applied via electron-beam evaporation with Ion-assisted deposition
4.Filter substrate is fine-optically polished to 1/4 wave and <30 parallelism over both surfaces
5.Good 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
6.Each filter comes with a plastic case with high pressure EVA case lining
7.Best used with a moderate to large aperture telescope and clear, dark skies
Specification:
1.Thin metal cells have a clear aperture of 26mm for 1.25 inch filters
2.Blocking area: 400-700nm
3.Transmittance: 80% at 486nmÂ
4.0.1% transmission Hg at 435nm and 578nm
5.0.1% transmission Na at 589nm
6.FWHM: 25±3nm
7.Thickness: 1.85mm
8.Surface quality: 60/40 (Refer to MIL-O-13830)
9.Thread Size: M28.5*0.6
10.Net Weight: 5.4g /0.19oz
WARNING:Â
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.
Package includes:
1 x SV132 1.25" H-Beta Filter
Details Pictures:
