The most popular filter for the study of Jupiter and Saturn. 3200 K to 5500 K. Enhances contrast of rills and festoons in Jupiter's cloud belts as well as details of the Red Spot. Brings out detail in Saturn's belts and polar phenomena. Very useful as a contrast-enhancing lunar filter.
Ed ~ With Jupiter dominating the night skies, this filter is semi-permanently attached to my planetary eyepiece. It really does bring out subtle detail on the planet. This filter is recommended for small to medium sized scopes.