Time-lapse photography is a technique whereby the frequency at which film frames are captured (the frame rate) is much lower than that used to view the sequence. When played at normal speed, time appears to be moving faster and thus lapsing. For example, an image of a scene may be captured once every second, then played back at 30 frames per second; the result is an apparent 30 × times speed increase. Time-lapse photography can be considered the opposite of high speed photography or slow motion. Processes that would normally appear subtle to the human eye, e.g. the motion of the clouds, sun and stars in the sky, become very pronounced.