Street Corner (1948)

Everyone has seen them, but not everyone has noticed them.  And even fewer fully understand the purpose of the circular scratches that appear about every twenty minutes in a film, like subliminal postage stamps.  They are cue marks (aka cue dots), and they are the projectionist’s friend.  Worldly Morlocks may fully understand the cue mark, but even so, let us still pause and celebrate the usefulness of the flickering dot, because the dot (like the projection system that necessitated its use) is gradually vanishing from the screen and will soon be a baffling artifact over which future film historians will scratch their heads.      

As you may know, feature films are generally shipped to theatres on multiple reels, each containing about 2,000′ of celluloid.  The reels were shown consecutively.  In order to avoid stopping the show to re-thread the projector every twenty minutes, theatres were equipped with two separate projectors.  This is known as a “change-over” system.  While projector one was showing reel one, the projectionist was busy threading projector two.  When reel one was just about to come to an end, the projectionist would fire up projector two and open the gate at the precise moment when projector one ran out of film.  Once projector two was up and running, the projectionist would return to projector one and thread up reel 3.  On and on this would go until the film’s end, and hopefully the audience would never be aware that projectors were being started and stopped every twenty minutes.

If you think it sounds nerve-wracking, it is.  I worked as a projectionist for a few years.  I still have nightmares.

Some trailers have cue marks: The Big Sleep (1946)

So how does a projectionist predict the split-second moment at which a projector is running out of film?  The cue mark, of course.

Each reel has two sets of cue marks — scratched into the emulsion, hole-punched into the print or the negative, sometimes round, sometimes square.  Each appears for about four frames (or flickers for about 1/6th of a second).  By the time they appear, the projectionist is (hopefully) standing ready with the carbon arcs burning and his/her hand on the engine switch.  At the appearance of the first set of marks, projector two is thrown into motion and given time to run up to speed (leader is passing across the lens but the audience doesn’t see it because the lens is covered by a douser).

About eight seconds later, there is a second blip of cue marks, meaning there is less than a second of film remaining in projector one.  At this point, the projectionist throws open the douser (automatically shutting the douser on projector one) and reel two bursts onto the screen.

A stretched cue mark indicates the film is anamorphic widescreen: Siberian Lady Macbeth (1961)

When one cue mark isn't enough: The Nashville Sound (1970)

If you weren’t already familiar with the cue mark, you are now.  And if you hadn’t noticed them before, now you won’t be able to ignore them.  Don’t curse them for spoiling a director’s composition or intruding upon the edge of an actor’s face.  Remember they are a part of film exhibition history, and were once an important part of the seamless moviegoing experience.

Soon, cue marks will be extinct, without having been given an obituary in the Times, or a few seconds in the Academy Awards’ annual roundup of the deceased.  It’s up to us to remember.