Time-lapse photography refers to shooting automatically and regularly in a long period of time (also known as low speed photography or delayed photography). It is a kind of photographic technology that shoots images or a video at a low frame rate and then play them with a normal or faster rate. Using a SLR camera to take time-lapse photography needs to wait for time intervals to get a series of photographs, which is impossible to entirely press the shutter by hand. Even worse, many cameras do not have an interval shooting function and have to get the assistance of an external timer.