For casual sky shooting, almost any design of camera will do, but it must have a B (for Bulb) setting for the shutter. This setting holds the shutter open for as long as the shutter button is pressed—an essential feature because most night-sky photos require exposures of several seconds, if not minutes. To hold the button down during these long exposures, you use a locking cable release, which screws into the shutter button.
The drawback of most new cameras is that their shutters are battery-operated. Relying on batteries is risky—they may fail in the cold night air or during long exposures. This is why many astrophotographers seek out mechanical cameras on the secondhand market. (Good models include 35 mm single-lens-reflex, or SLR, cameras such as the Canon FTb and Fl, Nikon FM2 and F3, Olympus OM-1 and OM-4T, and Pentax K-1000 and LX.) It might seem strange to forgo the electronic features that adorn today's cameras, but none of them is needed for astrophotography.
While a close-up of the Moon or a clear image of a faint nebula requires shooting through a telescope, many sky subjects can be captured with standard camera lenses. Lenses that have fixed focal lengths are usually of better quality and faster than zoom lenses. For 35 mm cameras, a set of three fixed lenses is useful: a wide-angle lens (one with a focal length of 24 to 35 mm), a normal lens (50 to 55 mm), and a short telephoto lens (85 to 200 nun). Try to choose fast lenses— these have a maximum aperture of f/2.8 or f/2.
For photographing the night sky, especially with color film, most of the filters employed by photographers and amateur astronomers are of limited value. Broadband LPR, or deep-sky, filters can help darken sky backgrounds but usually shift the color balance to green. A dark red filter will enhance nebulosity when shooting with the favored black-and-white film, Kodak Technical Pan 2415, or Tech Pan.