Colour Filters are a helpful tool allowing you to squeeze the most subtle details out of planetary views through the eyepiece.
The descriptions below will help you choose the most suitable colour filters for your intended target.
Contrasts strongly with blue-coloured features on Jupiter and Saturn, while enhancing red and orange features. Lightens red and orange features of Mars, while reducing or blocking the transmission, and thereby increasing the contrast, of blue-green areas. Useful in increasing the contrast of lunar features in telescopes 6″ aperture and larger.
#15 Dark Yellow
Useful in bring out Martian surface features and the polar ice caps.
Reduces transmission of blue-green wavelengths. Use on Jupiter and Saturn to enhance detail in the belts and polar regions. Sharpens boundaries between yellow-orange areas and blue-green regions on Mars, resulting in a darkening of edge-detail in the maria.
#23A Light Red
On telescopes of 6″ aperture and larger, the #23A does approximately the same functions as the #21 Orange filter, but with stronger contrast and enhancement of marginally defined blue-green surface detail. Also increases contrast between Mercury and bright blue sky during during twilight observations.
Strongly blocks the transmission of blue and blue-green wavelengths, resulting in very sharply defined contrast between blue-tinted cloud formations on Jupiter and the lighter-toned features of the disc. Also useful for delineation of the Martian polar ice caps and maria. Low total light transmission, so should only be employed on telescopes of 8” aperture and larger.
#29 Dark Red
Functions much like the #25A Red, helping with daylight/twighlight observation of Mercury and Venus (particularly the Venusian Terminator), the Martian Maria and polar caps, Jovian Belts and for Saturn’s clouds. Also handy for observing the transits of Jupiter’s moons across its disk. Only for use in large telescopes above 8″ aperture.
#38A Dark Blue
A popular filter for study of Jupiter’s disc, owing to the filter’s strong rejection of red and orange wavelengths. Increases contrast between the reddish belt structures and enhances detail of the Red Spot. Also useful for study of isolated phenomena, such as dust storms, on Mars, as well as the belt structure of Saturn. Increases contrast of subtle clouds markings on Venus. For telescopes 8″ aperture and above.
Strongly rejects red, yellow, and green wavelengths; useful for the study of Martian polar cap regions, and for the observation of occasional phenomena in the upper atmosphere of Venus. Enhances contrast between the rings of Saturn. Use only on telescopes of 8″ aperture and larger.
Excellent for the observation of Martian polar ice caps as well as yellow-tinted dust storms on the Martian surface. Increases contrast of red and blue regions in Jupiter’s atmosphere as well as in the cloud belts. Good for enhancing lunar detail. For 8″ telescopes and up.
#58A Dark Green
Use on telescopes of 8″ aperture and larger to reject blue- and red-toned structures on the surface of Jupiter and thereby increase their contrast relative to lighter parts of the disc. Also use for the enhancement of Saturn’s cloud belts and Polar Regions. Strongly increases contrast of Mars’ polar ice caps, and increases contrast of atmospheric phenomena on Venus.
The most popular filter for the study of Jupiter and Saturn. Enhances contrast of rills and festoons in Jupiter’s cloud belts, as well as details of the Red Spot. Brings out detail in Saturn’s belts and polar phenomena. Very useful as a contrast-enhancing lunar filter. For telescopes 6″ and up.
#82A Light Blue
Useful on the Moon, Mars, Jupiter, and Saturn, this subtle pale blue filter enhances areas of tow contrast while avoiding significant reduction of overall image brightness. Suitable for most telescopes.