This CRGB (Clear, Red, Green, Blue) filter set works best with high-quality reflectors, such as Ritchey-Chrétiens, that are intrinsically well color-corrected. It 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 reflector imaging, rather than refractor or camera lens imaging.

On the other hand, the near-IR blocked LRGB filter set #TB2LE27R 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 #TB2LE27R better suited for imaging with refractors and camera lenses, which often are not particularly well-corrected in the violet end of the spectrum.

A spectral “gap” between approximately 540nm and 640nm minimizes the effect of mercury and high and low pressure sodium city light pollution, as well as several airglow emission lines due to ionized nitrogen in our atmosphere.

This Astrodon E-Series 1.25” mounted CRGB filter set threads into any color filter wheel that accepts standard 1.25” threaded filters. Each is parfocal with Astrodon's high-performance narrowband (H-alpha, Oxygen III, etc.) and near-IR filters, as well as with each other. The filters come in a hard plastic snap-lid storage case.

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