Astrophotography

Astrophotography ranges from simple images of bright objects to very complex exposures designed to reveal objects that are too faint to observe with the naked eye. With only a few exceptions, almost all astrophotography employs time exposures since both film and digital cameras can accumulate and sum light photons over long periods of time. This is just one of many distinct aspects of astrophotography that sets it apart from conventional photography.

Astrophotography poses challenges that are distinct from normal photography, because most subjects are usually quite faint, and are often small in angular size. Effective astrophotography requires the use of many of the following techniques:

* Mounting the camera at the focal point of a large telescope
* Film emulsions with low light sensitivity or specialized CCD cameras
* Very long exposure times and/or multiple exposures (often more than 20 per image).
* Accurate tracking of the subject to compensate for the rotation of the Earth during the exposure
* Use of filters to reduce background fogging due to light pollution of the night sky.