The IR-Block Filter from Celestron is a screw-on fully multicoated filter for cameras with standard C-threads. The dichroic coatings on this filter block infrared (IR) light, while also passing more than 94% of visible light to the camera's imaging sensor. This is important for astrophotography because IR light can cause interference with sensors and cause images to appear out of focus. With IR light blocked, images will appear sharper with greater colour balance. The filter was designed to be used with Celestron's Skyris colour eyepiece cameras, but will work with any camera that has standard filter C-threads.