This filter finds application in planetary imaging. It is a favorite of webcam users when imaging planets - especially Mars. The passband begins in the deep red region at 670nm and extends well into the infrared. This long wave light can be used in IR LRGB imaging to produce a sharper luminance image for the best planetary contrast. Often the atmospheric seeing is much steadier at these IR wavelengths. Images taken with IR as luminance channel have produced some of the finest Mars pictures during the last opposition. Contrast on Jupiter and other planets is also visibly enhanced
Both surfaces are optically polished to produce diffraction limited images and professionally coated to very tight tolerances.