| article: Guide to Choosing, Using and Buying Astronomical Filters for Digital Cameras, Film Cameras and Eyepieces |  | The main purpose of astronomical filters is to block unwanted light and to let pass the wanted one. They are very important for sucess in visual observation as well as for astrophotography. Depending on the color the filter is made for there is a huge number of possible uses:
- Improving Planetary, Lunar or Comet Detail
- Improving Contrast of Nebulae and Galaxies
- Fighting against Light Pollution
- Making Color Photos with a monochrome Digital Camera (CCD)
|
Improving Planetary, Lunar or Comet Detail
| | These filters are enhancing one color while supressing the others. This increses the contrast of special subtle detail. They must be matched to the details of interest. |    | Light Red (#23A)
This filter increases the contrast of a planet against the blue sky when observation during twilight or daytime is necessary. It is also useful for CCD imaging of deep sky objects in the presence of the moon or week light pollution. |   | Yellow-Green (#11)
This filter helps to reveal fine details in the cloud bands of Jupiter as well the softer bands of Saturn. Also it is helpful against ultraviolet light when photographing with film and a refractor. |  | Light Green (#56)
Gains contrast of some lunar details. Brings out the area arround the polar caps of Mars. Accentuates red features as the Great Red Spot of Jupiter. |  | Light Blue (#82A)
Increases the contrast of Mercury and Venus when watching them against an orange twilight sky. Also reduces glare of Moon. Supresses chromatic aberration when using an achromatic refractor. |  | Dark Blue (#38A)
Enhances dust storms and polar caps on Mars. Increases contrast of Comet's tails. |
Improving Contrast of Nebulae and Galaxies and fighting against Light Pollution
| | These filters are a must if you cannot watch under really dark skies. They are supressing the colors of streetlamps and other sources of light pollution. |  | SkyGlow Filter
This filter is a selective Filter. It blocks several wavelength where street lamps and the moon are affecting the sky background.
These colors are mostly in the green spectrum. Therefore this filter can be used to get rid of hallo around bright stars in an Achromatic Refractor. You will just focus to the red/blue focus instead of green automatically.
For a test report for photographic use click here. | | | Oxygen III Nebula Filter (#910X)
This filter is a narrow band filter and very much designed to enhance the contrast the Oxygen III emission of Nebulae. It gives a much better contrats for this type of object compared to broadband filters. |  | Nebula Filter (#911N)
This filter is a broadband filter and therfore also useful for photography. It increases the contrast with the surrounding sky and the deep sky object of interest. |
Making Color Photos with a monochrome Digital Camera (and Filter Sets)
| | These sets are providing a useful selection of color filters. Either for the special purposes (see above) or for Red-Green-Blue color imaging with a monochrome digital camera (CCD). | | | Filter Set
This filter set includes the Red, Green and Blue necessary for RGB images. Also included is an Orange, Yellow, Light Blue and Grey filter. The Grey filter is especially ueseful for damping the bright light of the moon without affecting the color balance. |
|
|
|