From: “Rethinking the Art of Subtitles” by Grant Rosenburg, Time

If subtitles “aren’t invisible, you fail,” says Henri Béhar, subtitler of notable films such as Brokeback Mountain, Boyz in the Hood and Good Will Hunting. “The titles should subtly give people the impression that they are understanding the characters speaking, not reading words on the screen.” Trying to translate one language to another in the course of a film has challenges and limitations that apply to dubbing as well as subtitling — unlike literature which has the safety net of footnotes, film subtitlers have to make it work in the moment, all while trying to adapt wordplay and cultural references.

Once in a while, subtitlers do get their due. Jacqueline Cohen, responsible for all of Woody Allen’s films since 1989’s Alice, says that “whenever Woody comes to town, he always mentions that the reason his films are so successful in France is thanks to the person who does the subtitles.” No quick task, considering the talky nature of the prolific filmmaker’s almost annual releases. “Action movies average about 700 subtitles — Woody’s, between 1,500 to 2,000,” says Claude Dupuy, the director of subtitling at LVT Laser Subtitling, which handles more than 600 films per year.

At LVT and other companies, a person watches the film scene by scene, doing what’s known as spotting — marking time according to the timecode, the film’s official clock — the start and end point of each spoken line of dialogue. Then the subtitler goes to work, balancing the challenge of conveying meaning accurately within the confines of space and the roughly 1.5-second-long display allotted per subtitle. The reality is that despite the reputation of subtitling over dubbing as a form of cultural purity, the eye reads slower than the ear hears, meaning that more than a third of a film’s dialogue is sacrificed for what is most essential. The general rule is no more than 45 characters per line, even though widescreen movies could fit longer sentences (says Dupuy, “it shouldn’t be like watching tennis”).

There are logical rules as well, such as finishing a subtitle when a character stops speaking and not extending it over a cut, which can be disorienting. Good subtitles work with the rhythm of the scene, based on accurate spotting that captures that timing.