Astro-Tech #21 Orange 1.25" Color Filter

This #21 orange Astro-Tech 1.25" eyepiece filter is useful in improving contrast when observing the Moon and all planets out to Saturn in telescopes 6" to 8" in aperture and larger, particularly if combined with a polarizing or neutral density filter. 

Recommended applications for this filter:

Moon - Very useful for improving contrast between lunar features in scopes 6" and larger, with or without polarizer or neutral density filter.

Mercury - Darkens terrestrial sky during daylight viewing to enhance rarely visible subtle surface albedo differences.

Venus - Darkens terrestrial sky during daylight viewing to show the phases more clearly.

Mars - Increases the contrast of polar caps, frost areas, low clouds, and dust storms against the ochre deserts. Also sharpens the boundaries of yellow dust clouds.

Jupiter - Brings out structure in the belts and enhances festoons and polar regions.

Saturn - Improves the structure of atmospheric bands and highlights blue-toned polar regions.

Comets - Can be piggybacked with #38A filter to improve contrast of orange Sodium D lines in comet gas tails in scopes 10" and larger. Enhances the definition of comet heads and dust tails in 10" and larger scopes.

Solar - Used to give correct color rendition of the Sun when using a Mylar solar filter.

 46% transmission