Sometimes when I watch movies I notice a mark ( circle ) that shows for less than a second on the top right corner of the many movies.

I wonder what is that and why they have it?


This is a cue mark that tells the projectionist that it is time to change the film reel.

A pair of cue marks is used to signal the projectionist that a particular reel of a movie is ending, as most movies come to theaters on several reels of film lasting about 14 to 20 minutes each (the positive print rolls, themselves, are either 1,000 feet or, more commonly 2,000 feet, nominally 11.11 or 22.22 minutes, maximum, with more commonly an editorial maximum of 10 or 20 minutes). The marks appear in the last seconds of each reel; the first mark, known as the motor cue, is placed about 8 seconds before the end of the picture section of the reel. The second mark, known as the changeover cue, is placed about 1 second before the end. Each mark lasts for precisely 4 frames (0.17 seconds).

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    Do the projectionists really sit there for 10 or 20 minutes doing crossword puzzles and then focus on the top right corner until it is time to change? How exactly does the change of reels go down? Do they have to get the perfect timing so nobody notices? – Ian May 24 '17 at 7:26
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    Some projectionists push a coin (a quarter, for example) into the film reel, so that it falls out as the film un-spools and provides an audible alert. #columbo – Grimm The Opiner May 24 '17 at 8:30
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    I worked as a projectionist - yes, that's exactly how it works. But usually the cuedots fall on a scene change, with some overlap - so you don't notice the transition, because one seen is slightly longer than others. You have two projectors and just press a 'open/close' shutter button that switches between them. More commonly though, we'd splice together 3 reels at a time, to make a single 60(ish) reel, and only changeover once per film. – Sobrique May 24 '17 at 8:36
  • @Sobrique these days, would splicing be less common since most film prints are getting old, in order to minimise the risk of damage? Or is there really not much more risk when splicing than with other techniques? – Muzer May 24 '17 at 8:43
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    Prints are getting older, but ... the film industry is mostly moving to digital anyway. So it's a bit of a moot point. But certainly for the older stuff, we'd hear the 'click-click' of a splice going through the projector quite frequently. You really don't notice single frames going missing. (The Star Wars trailers we had, they audited to make sure projectionists weren't stealing frames...). But splicing two together is usually 'tape one to the other, undo it after' so there's not a cut in the film. – Sobrique May 24 '17 at 8:46

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