These CRGB filters works best with high-quality reflectors, such as Ritchey-Chrétiens, that are intrinsically well color-corrected. They should be parfocal for systems as fast as f/3.5. The clear (no near-IR blocking) filter in this set may produce bloated stars if your optical system has poor near-IR focus, as is the case with many camera lenses and refractors, which is why this non-near-IR blocked CRGB filter set is generally the best choice for imaging with reflectors, rather than with less well-corrected refractors or camera lenses.

On the other hand, the near-IR blocked LRGB filter set #TB2LI50R has reduced UV contribution in its luminance and blue filters. This reduces star bloat in optical systems that are not well color-corrected. This makes LRGB filter set #TB2LI50R best suited for imaging with refractors and camera lenses, which often are not particularly well-corrected in the violet end of the spectrum.

A narrow spectral “gap” between approximately 565nm and 600nm minimizes the effect of mercury and high and low pressure sodium city light pollution, as well as an airglow emission line due to ionized nitrogen in our atmosphere.

These Astrodon I-Series 50mm unmounted round CRGB filters thread into any color filter wheel that accepts standard 50mm threaded filters, or into the color filter wheel integrated into SBIG Research Series cameras. Each is parfocal with Astrodon's high-performance narrowband (H-alpha, Oxygen III, etc.) and near-IR filters. The filters come individually wrapped in a hard plastic snap-lid storage case.

For more detailed information on Astrodon filters, click on the “Astrodon Generation 2 Filters” icon above.