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2" OPT Triad Triband Narrowband Filter

OPT Radian Triad Ultra Quad-Band Narroband Filter

The Triad filter has now been improved! With Triad Ultra, you now have narrower bandpasses, more light pollution reduction, higher contrast, better separation between H-beta and OIII channels, and sensitivity on Sulfur II emission lines. Like the original Triad filter, the Triad Ultra is designed to work with color cameras, but also as a narrowband luminance filter for monochrome cameras.

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Entrega entre 8 y 10 días laborables
Entrega entre 8 y 10 días laborables

The Triad Ultra is 100% American made and uses advanced multi-coatings and extreme tolerance glass to ensure it is always consistent and accurate. The thickness of the filter is 3 mm.

Since the filter has extremely narrow bandpasses, telescopes with focal ratios faster than f/4 will move the transmission out of band. Telescopes with focal ratios between f/2.9 and f/3.9 are compatible with Triad Ultra, with lower transmissions. Telescopes with focal ratios faster than f/2.8 are incompatible with the Triad Ultra filter.

Lines of transmission:

H-Beta: 79% maximum transmission, 5nm FWHM

O-III: 97% maximum transmission, 4nm FWHM

H-Alpha: 87% maximum transmission, 4nm FWHM

S-II: 90% maximum transmission, 4nm FWHM.



Connection (to the telescope)  2" 
Frame  2" 


Series Triad Ultra
Type Filters 

Area of application

Anti light-pollution yes
Hydrogen nebulae yes
Planetary nebulae yes
Supernova remains yes
Useful for photographs yes
Visually useful no
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