Glossary
Intervalometer
A remote timer that triggers a camera shutter automatically at set intervals, essential for long-exposure astrophotography and star trails.
An intervalometer is a remote shutter timer, either a standalone device or a built-in camera feature, that automatically fires a camera's shutter at set intervals for a set duration or number of exposures. In astrophotography, this matters because sharp images of faint objects require long exposures repeated many times in a row, a sequence far too tedious and shake-prone to manage by pressing the shutter button by hand each time.
Beyond single long exposures, an intervalometer is what makes star trail photography and time-lapse sequences of the night sky possible, since it can be set to fire dozens or hundreds of consecutive frames at a fixed interval while the photographer steps away from the camera entirely, avoiding any vibration from touching the body during the exposure.
When choosing one, check compatibility with the specific camera model, since connector types and menu support vary between brands, and look for a model that can be set below the camera's built-in maximum exposure time, usually 30 seconds, if longer single exposures are the goal. A common mistake is forgetting to test the full intended sequence length before a session, only to discover a battery or memory card runs out partway through a planned all-night sequence.