Visual filters enhance the contrast of certain features or objects by blocking either light of the same color as that feature, or light of the same color as the feature's surroundings. Most visual filters are relatively clear in the near-IR, limiting their value for CCD observing.
Wratten #11 filters have been promoted for a variety of uses, including the belts of Jupiter, the rings of Saturn, and Uranus and Neptune. We have not yet tested all these claims.