In film editing, transition refers to how one shot ends and the next begins, and the filmic device that bridges one to the other. Many different types of transitions have been employed since the early years of cinema. Some are outdated, used mainly to refer to those first years, but others are still greatly used today. Each type invokes a different emotion. Understanding those emotions is essential to master editing.
The most basic and common type of transition is the cut. A cut happens when one shot instantly replaces the other. Cuts are so widely used that feature movies normally count thousands of them.
Cuts are essential for the effects of juxtaposition, especially as demonstrated by the Kuleshov Experiment. Although most cuts exist simply for a technical need, the abrupt replacement of one shot by the other often demands a certain interpretation from the viewer.
Consider the following example from the very beginning of Three Days of Condor (1975). Note that this early in the movie the main character, Joseph Turner (Robert Redford), has not been introduced yet.
The obvious understanding is that the man on the bike is Turner (mentioned on the first shot), and that he’s riding to work. Though the audience’s assumption may not be a correct one, the editor must be aware of the implications inherent to the way he cuts a scene.
Cuts became industry standard for two reasons: First, during the early years of cinema, when editing actual film, the editor could very easily cut the celluloid strip with a blade or scissors and splice it together. Any other type of transition would require further processing from a specialized lab; therefore increasing costs. Second, the other types of transition are more distracting. Cuts allow for a better flow of the movie.
Fade ins and fade outs are the second most common type of transition. Fade outs happen when the picture is gradually replaced by black screen or any other solid color. Traditionally, fade outs have been used to conclude movies. Fade ins are the opposite: a solid color gradually gives way to picture, commonly used in the beginning of movies.
Despite being the second most used transition, fades are seldom adopted by editors. An average feature film will have only a couple of fades, if that. Fades are used sparingly because they imply the end of a major story segment. Fades are also utilized when allowing the audience time to catch their breath after an intense sequence. In Quentin Tarantino’s Pulp Fiction (1994), one fade out takes place right after Butch (Bruce Willis) rams his car into Marsellus Wallace (Ving Rhames), an unexpected accident that drastically alters the lives of those two characters.
Also known as overlapping, dissolves happen when one shot gradually replaces by the next. One disappears as the following appears. For a few seconds, they overlap, and both are visible. Commonly used to signify the passage of time.
Wipes are dynamic. They happen when one shot pushes the other off frame. George Lucas deliberately used them throughout the Star Wars series.
An old-fashioned transition hardly employed today is the iris, when a circulars masking closes the picture to a black screen. Irises are found in some cartoons like this example from Betty Boop:
Nowadays,d editing programs have introduced several other types of irises, like a star or heart. Though they have no place in serious filmmaking, those are great tools for homemade videos.