The Celestron IR Cut-Off Filter designed for the Skyris Colour CCD Camera, blocks infrared light (IR) while passing more than 94% of the entire visual spectrum. This becomes important as the Skyris colour planetary cameras are highly sensitive to infrared light, & as not all telescopes are designed to correct for IR light, the resultant image can often look defocused. By blocking infrared (IR) light the greatest colour balance & sharpness is maintained as well as colour fidelity.