Lens Flare is what happens when you point a camera toward the sun or other really really bright object, and the light bounces around inside the lens like a pinball machine, making a bunch of shiny circles all over the image. So called "cinematographers" (the people that make the camera run on movies), used to avoid lens flares lest they get fired, or worse. But the use of psychedelic drugs in Hollywood in the late 60s and 70s made lends flares cool, so now the cinematographer people point the camera at bright lights as often as possible. This can be seen prominently in the recent movie "Star Trek" as directed by J.J. Abrams.
In the early days of cinema, cinematographers would be fired for allowing lens flare to occur at all.
In 1930s to 1945 German Cinema, the "FilmVorFührApparatusMakinWrkinMitDasBlinkinlitePersonen" (the german word for cinematographer) would be executed by firing squad, or made to sit in a pizza oven until roasted to a crisp, if he allowed for a lens flare to occur.
The crew of the 1969 film "Easy Rider" decided to see if they could make an entire movie while high on drugs, in particular, LSD. This requires a special camera rig that could be operated while high. The camera rig was found frequently pointed at the sun because, as one camera operator said "Wow! look at that thing! it's BRIGHT!". When in the screening room, when shown the lens flared and over-exposed film, the cast and crew were like "WOAH! that's COOL!". Similarly drug induced audiences agreed, and the lens flare was a big hit.
- Leni Riefenstahl was the one filmmaker allowed to use the occasional lens flare, as she was sleeping with Hitler and thus granted immunity.