Stretching the grayscale Even adding several images may not be enough to make faint objects bright enough for a good picture. The moon is an excellent target for a digital camera on a telescope. It's possible to use fast exposures and all levels of magnification. Sometimes turbulence in the air causes the image to blur, but another advantage of the digital camera is that you can take lots of pictures and select the best. I only bought my digital camera in February, and there haven't been any planets in a good position for observing since then.
Planets are difficult to photograph because they are small and more weakly lit than the moon.
Greater magnification tends to spread out the light and to amplify atmospheric distortions. If you have a telescope that gives good views of the planets, then you may be able to get good photos, but expect to take lots of bad ones for each good one. Star clusters are good targets because the stars are point sources of light and do not get spread out by higher magnification. Using the image adding technique described above, it is possible to get good pictures of many of the brighter globular clusters and open clusters. In the July 2000 issue of Sky and Telescope , I noticed an article about measuring the separation and position angle of double stars.