The film could not just roll continuously; in order for the picture to appear clearly and coherently, a shutter was necessary to open and shut multiple times upon each small strip, producing a subtle flickering effect. Because the shutter speed was so fast, we barely noticed it, and our brains would splice the images together without interruption. But in the early days of cinema, when the shutter speed was slower, the flickering was more apparent. An early slang term for movies was “flicks.”
