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San Diego CityBEAT has a nice profile of astrophotographer Eric Blackhurst, manager of Oceanside Photo and Telescope, in today’s issue. An excerpt:

Counter-intuitively, deep-space photography requires less darkness than standard visual astronomy, because with long exposures, a camera can create an image out of what would be virtual darkness to the human eye. “With a 4-inch telescope, and a five-minute exposure time, you can see more than you can with your eye through the largest amateur telescopes,” Blackhurst says.

So in order to photograph these very faint objects, it’s necessary to use a very slow shutter speed, one not measured in minutes but hours… That exposure time requires a telescope mount that rotates along with the earth, so that stars appear as points of light and not as long trails…

“There’s always a drive to go deeper, not in terms of distance, but in terms of dimness. You can snap a picture of Andromeda in 30 seconds, but detail builds and builds as you get into three- and four-hour exposures,” he says.

The Exploratorium has a slideshow of Eric’s work taken last March in Turkey, during the total solar eclipse.

If you’d like a daily fix of astrophotography, check out NASA’s Astronomy Picture of the Day. Wikipedia also has a fairly detailed overview, with gallery, on the topic.