Most of the red, orange, or green filters recommended for observing Mars are made of ordinary dyed glass. Each passes only a broad swath of a single color, blocking all other colors, for a brute-force enhancement of one specific type of Martian feature or another. The TeleVue Bandmate Mars Type A filter is a more sophisticated dual band interference filter. It has different multi-layer ion-deposited dielectric coatings on each side of its BK-7 optical glass substrate. They selectively and simultaneously pass the red and the green portions of the visible spectrum, while rejecting all other visible colors. The effect is to enhance detail on the Martian surface while preserving the natural color of the polar caps and rest of the surface. This multicolor approach provides a more natural view of Mars, and a more realistic contrast enhancement, than the broad brute-force approach of a dyed-glass color filter that turns the planet varying shades of a single unnatural color.

The filter is made of polished optical grade BK7 glass to insure no image degradation due to quality of the substrate. Its ion beam deposition produces hard, stable coatings that resist changes due to temperature and humidity. The use of dielectric coatings, rather than dyed glass, gives high transmission and better blocking of unwanted wavelengths. This yields higher contrast images and a more natural color spectrum. The filter’s aluminum cell is precision machined and laser etched. The filter is supplied in a protective plastic case.