Astrophotography

From ArticleWorld

Astrophotography is a specialized form of photography where the photographer can capture distant images on film that are not visible to the naked eye, such as planets, stars, star clusters, and galaxies. Astrophotography requires the use of specialized cameras that are capable of long exposure times.

Cameras

Cameras that are used for astrophotography are equipped with special features, which include the capability of being mounted to a large telescope and following the subject, while taking into consideration factors such as the Earth’s rotation and movement. Filters that minimize fogging caused by light pollution are also frequently used with the camera.

History and Development

In 1840, John William Draper developed the first astrophoto when he took a photograph of the moon. Forty years later, his son Henry Draper took the first ‘deep sky’ astrophotography when he took a photograph of the Orion Nebula. In these early days, astrophotography employed the use of emulsions. The gas hypersensitivity of emulsions are designed for low-light and hence, were ideal for creating photographs of the night sky and far away objects that were dimly lit. Amateurs that are experimenting with taking astrophotographs, continue to use emulsions. However, with the recent developments of cheaper and higher quality alternatives, even amateur astronomers and astrophotographers are turning to CCDs.

CCD technology developed in the early 1990s and is the preferred method of taking astrophotographs for professional purposes and in observatories. CCDs offer photographers advantages such as responding in a linear fashion and greater sensitivity. They also function best under cryogenic cooling, biasing, and when varying pixel sensitivity is taken into consideration. CCDs however possess the disadvantage of offering a limited depth of view, which is a factor taken into consideration by many amateur astronomers who want to take photographs of distant stars in relation to their environment.