A DayStar UV/IR cut filter is a critical component in energy rejection for a small refractor, reflecting heat back out of the front of the refractor rather than allowing it into the Quark. It allows visible light through and blocks or reflects invisible ultraviolet and infrared rays. To the human eye it appears like a clear piece of glass.

Larger refractors (above around 80mm) will need an additional front-mounted energy rejection filter as the larger aperture allows more light (and hence heat) in.

The 2” UV/IR Cut Filter lets the full range of sensitivity of the human eye pass, and blocks all other parts of the spectrum in the UV and IR. The 2” UV-IR Cut Filter is the ideal choice as a luminance filter for any kind of digital photography. Because of the perfect blocking of UV and IR, all optical problems in these parts of the spectrum are avoided. The 2” UV/IR Cut Filter blocks the heat from reaching your filter and diagonal as well. This filter is optimized for systems with focal ratios between f/0.5 and f/50. The typical transmission is higher than 99%.