Color filters can be very useful for enhancing your views of the Moon and the planets. Depending on the atmospheric conditions, the telescope being used, the observer's experience, and the planet being observed or photographed, the advantages of color filters can be anywhere from subtle to dramatic. The right filter can make all the difference between seeing several small craters in the floor of Clavius on the Moon or not; seeing five or six swirls in Jupiter's belts or not; or seeing the inner Crepe Ring of Saturn or not.
Agena's 2" color/planetary filters are manufactured from the purest optical glass and are dyed-in-the-mass (not simply "color coated") for premium performance. They thread into the barrels of virtually any 2" telescope eyepiece. Each filter cell has a male and female 2" filter thread (M48x0.75) on opposite sides, so multiple filters can be stacked to achieve selective filtration of the visual color spectrum. The clear aperture is 43mm and each filter comes in a protective plastic storage case.
The #15 Dark/Deep Yellow Filter is used to bring out Martian surface features and the polar ice caps. It darkens Maria, lightens orange-hued desert regions and sharpens boundaries of yellow dust clouds. Used on Jupiter and Saturn, it penetrates and darkens atmospheric currents containing low-hue blue tones and is useful for polar-region studies. It can also be used to enhance the orange and red features (bands and festoons) on these planets and for low-contrast cloud detail on Venus. For Uranus and Neptune the filter improves detail in larger telescopes (11" aperture and larger). For comets, it enhances tail definition.
Try it also on lunar surfaces as well as for daylight observation of Venus and Mercury.