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Deep-Sky Photography Made Easy

by Alan Dyer

Piggyback photography
In piggyback photography, you use a telescope's mount to track the sky, but the camera shoots through its own lens, not through the telescope.
Night Sky: Craig Michael Utter
There's no more seductive image in astronomy than a picture of the night sky filled with stars and colorful glowing clouds of interstellar gas. You know, the kind you see in books and magazines. These images usually come from multimillion-dollar telescopes. But it doesn't take a mountaintop observatory to capture panoramic deep-sky vistas. They're within reach of anyone with modest stargazing equipment and access to dark, rural skies. The technique is called piggyback photography, and today's high-speed color films and digital cameras have made the process easier than ever before.

The richest star fields in the sky are found along the Milky Way, formed by the spiral arms of our home galaxy and well-placed during late summer. The exposure times needed to record the Milky Way typically last a few minutes. For this you'll need a camera with a B ("bulb") setting on the shutter to permit long exposures and a telescope capable of tracking stars as they move from east to west. But you don't shoot through the telescope itself — it's the mount you want, to serve as a stable, motorized platform. You attach your camera securely to the telescope's tube assembly. It then rides along, piggyback style, as stars are recorded by the camera's lens.

Without motorized tracking, Earth's rotation would cause stars to trail across a camera frame, an effect noticeable with even a 30-second exposure. Star trails can make for great astrophotos, but for rich, star-studded time exposures, accurate tracking is the key.

The beauty of piggyback shooting is that if the mount is set up correctly and tracks well, all you need to do is lock the camera's shutter open and walk away. You don't need specialized and expensive guiding gear. While the camera and mount do their work unattended, you can sit back, relax, and enjoy the night sky.



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