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.
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.
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