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OPT Radian Triad Ultra Quad-Band Narroband Filter
The Triad filter has now been improved upon! With the Triad Ultra, you now have narrower band-passes, more light pollution reduction, higher contrast, better separation between H-beta and OIII channels, and sensitivity in the Sulfur II emission lines. Like the original Triad filter, the Triad Ultra is designed to work with color cameras but also as a narrow-band-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. Filter thickness is 3mm.
Since the filter has extremely narrow band passes, telescopes with focal ratios faster than f/4 will move transmission off 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.
H-Beta: 79% Peak Transmission, 5nm FWHM
O-III: 97% Peak Transmission, 4nm FWHM
H-Alpha: 87% Peak Transmission, 4nm FWHM
S-II: 90% Peak Transmission, 4nm FWHM