Equipment - Filters

These are color optical filters primarily for visual use.
The filters I own and their typical applications are listed below:

  #8: Light Yellow - 83% Transmission
A light yellow filter helps to increase the detail in the maria on Mars, enhance detail in the belts on Jupiter, increase resolution of detail in large telescope when viewing Neptune and Uranus, and enhance detail on the moon in smaller scopes.

  #12: Yellow - 74% Transmission
Yellow filters help greatly in viewing Mars by bringing out the polar ice caps, enhancing blue clouds in the atmosphere, increasing contrast, and brightening desert regions. Yellow also enhances red and orange features on Jupiter and Saturn and darkens the blue festoons near Jupiter's equator.

  #23A: Light Red - 25% Transmission
Light red filters help to make Mercury and Venus stand out from the blue sky when viewed during the day. Used in large telescopes, light red sharpens boundaries and increases contrast on Mars, sharpens belt contrast on Jupiter, and brings out surface detail on Saturn.

  #25A: Red - 14% Transmission
Red provides maximum contrast of surface features and enhances surface detail, polar ice caps, and dust clouds on Mars. Red also reduces light glare when looking at Venus. In large telescopes, a red filter sharply defines differences between clouds and surface features on Jupiter and adds definition to polar caps and maria on Mars.

  #47: Violet - 3% Transmission
Violet is recommended only for use on large telescopes. A violet filter enhances lunar detail, provides contrast in Saturn's rings, darkens Jupiter's belts reduces glare on Venus, and brings out the polar ice caps on Mars.

  #58: Green - 24% Transmission
Dark green increases contrast on lighter parts of Jupiter's surface, Venutian atmospheric features, and polar ice caps on Mars. Dark green will also help bring out the cloud belts and Polar Regions of Saturn.

  #80A: Blue - 30% Transmission
A Blue filter provides detail in atmospheric clouds on Mars, increases contrast on the moon, brings out detail in belts and polar features on Saturn, enhances contrast on Jupiter's bright areas and cloud boundaries. A blue filter is also useful in helping to split the binary star Antares when at maximum separation.

The nominal spectral profile for filters #8, #12, #23A, and #29 are shown here and #47, #58, #80A are shown here.

Here are some of the special purpose filters I use:

  IR Block (GSO, Meade): Useful for CCD imaging, especially for refractors and catadioptic telescopes which don't bring IR radiation to the same focus as visible light. As CCD's are sensative to IR light, this filter blocks wavelengths past about 700nm to keep images in focus.

  Orion Sky Glow Filter: Broadband light pollution Filter.

The nominal spectral profile for these filters is here.