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How Telescopes Work


Astrophotography is a favorite pastime of many amateur astronomers, but it requires much patience. Astrophotography can be done with conventional film cameras (35 mm), special cameras (Schmidt cameras), or CCD/digital cameras. In fact, a current area of debate seems to be conventional film astrophotographers versus digital astrophotographers. Each type has advantages and disadvantages; for information on these, see the links section.

There are several ways to do astrophotography:

  • Using a camera (with or without a telephoto lens) mounted to a movable "Scotch mount" on a tripod.
  • Using a camera (with or without a telephoto lens) "piggybacked" on a telescope (the telescope is used as a guiding lens).
  • Using a camera mounted to a telescope (the telescope acts as the camera lens).

Here are some basic pieces of equipment needed for astrophotography:

  • An equatorial telescope mount to track the motion of the object. Some film exposures require you to track an object for up to an hour.
  • A photographic "T" mount to attach the camera to the eyepiece holder.
  • A shutter cable, if you use a 35-mm camera (manual mode).
  • A guiding eyepiece with an illuminated reticle, to keep the target in the center of the field as it moves.

Large aperture reflecting telescopes tend to be a favorite of astrophotographers for their light gathering ability.

Astrophotography requires much dedication, but it can be incredibly rewarding to review and display your own work. Also, photographs can be used to gain scientific information about astronomical objects. See the links section for further details on astrophotography.

This has only been a brief overview of the projects you can undertake with your telescope. Again, what you plan to observe will be one of the most important factors in your choice of telescope. Whether you are a casual observer who simply appreciates the beauty of the heavens, or a serious, science-oriented observer, the night sky has plenty to offer.

On the next page, we'll learn about some common telescope features.