Tracked Shots on Equatorial Mountings
One axis of this mount, called the "polar axis" aligns parallel to the Earth's axis and a motor and gear turn the scope around this axis at the exact same rate that the Earth turns so that an object in the sky stays stationary in the telescope.This type of mounting allows the telescope and camera to track or exactly follow the sky as the stars appear to move across the sky as the Earth turns underneath them.
An equatorial mounting that is correctly polar aligned can track on the stars to allow exposures of many minutes. A camera with a normal lens can be mounted "piggyback" on top of the telescope and wide angle, normal, and short telephoto focal length shots taken while the mounting tracks the stars.