Lunar and Planetary Filters
Lunar and planetary filters are used to reduce brightness and glare, and can also reveal subtle detail that is lost when one color dominates the object. Observing the moon with any telescope larger than three inches in aperture is a lot like shining a flashlight into your eye. Lunar filters are color neutral but reduce brightness and glare, making your observations more comfortable and enjoyable. Variable polarizing filters are useful for both lunar and planetary observing, and are also color neutral. These filter allow you to adjust the light transmission of the filter to suit the target.
Color planetary filters are used to reveal subtle detail that may otherwise be lost when one color dominates the object. Mars is a classic example, where the color red is so predominant that other details are often missed without a suitable filter. Using an orange or light red filter blocks some of the red light and makes darker surface details more visible.