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Revision as of 14:53, 4 April 2017

Neutralizing the Intermittent

Sometimes called "neutralizing the Geneva" which refers to the internal mechanism in projectors that use a Geneva drive. Making sure your intermittent is both centered (we'll go over how to do that in the framing mechanism section) and in a neutral position in relation to the Geneva mechanism is a must before starting any show. Neutralizing the intermittent must be done before threading a projector EVERY SINGLE TIME no matter what, regardless of whether or not your framing has been re-adjusted.

  • To place it in a neutral position, place your fingers on the intermittent sprocket and advance manually. The intermittent sprocket does not rotate continuously, but in steps. Once it's completed a full rotation and stopped, it will be in a neutral position. You should be able to rock the manual advance back and forth a little bit with the intermittent sprocket remaining still.

The Framing Mechanism

Intermittent sprocket on a Simplex XL projector. Observe its range of motion and set to the center of its travel before threading.
  • From the Century Projector Manual: "Rotation of the FRAME knob on the front of the projector causes the intermittent to move up and down. Observe the upper and lower limits of intermittent travel, and position the intermittent at the center of its travel. This will insure adequate movement up or down to correct accidental misframes. Always "center" the intermittent in this manner before threading."
  • If you are working with a Simplex XL you'll noticed the intermittent does not move up and down like the Century, but rotates. The same principle applies, position the intermittent at the center of its rotation, make sure the intermittent is in a neutral position, and then thread the film.
  • If you're working with a Kinoton you won't be able to see external evidence of the framing mechanism having been moved. But it is still very important that the intermittent is in a neutral position before you thread. To check for this, put your finger on the sprockets of the intermittent as you manually advance. Once you feel the intermittent make it's rotation, advance a tiny bit more (the intermittent should be still) and stop.

Failure to do this can not only cause frame mishaps (which are embarrassing!) but other issues:

  • If the film is threaded while the intermittent is in the incorrect position and then re-adjusted as the film is running it can cause your top and bottom loops to become either too small or too large, increasing the chance that they will be hitting a hard surface within the projector, causing scratches. "Slap scratches" are often caused by this very thing.
  • If the framing is adjusted while the film is running and the operator fails to reset it before the next reel, you may attempt to adjust the framing AGAIN and discover that you have reached the limits of the framing mechanism. I.e you adjust the framing all the way in one direction but the picture is still out of frame on screen, and you can move the framing mechanism no more. At this point the operator must stop the film, reset the framing mechanism to center, neutralize the geneva, re-thread, and start the film again. Not only is this bad showmanship, but stopping the film on picture can cause scratches.


After going through the processes above to ensure correct framing, you should always advance manually a foot or two (or pulse the motor if possible), make sure the intermittent is in neutral position, and then check the position of the film in the gate AGAIN to make sure it's in frame.


Things to look for during the Inspection process in regards to framing are:

  • check splices! Make that any frames spliced together are COMPLETE frames. The number of perforations (or sprocket holes) in a complete frame will depend on what film gauge you are working with, 4 perfs for 35mm, 2 perfs for 16mm, 5 perfs for 5/70mm etc. If an incomplete frame (a frame a perf or two cut off) attached to a complete frame will cause the film to "jump" out of frame during your screening.
  • make a note of whether the print has a hard matte or not. Some prints have a hard matte for some scenes and no matte for others. Make a note if the lab splices in an anamorphic print seem larger than normal or might be visible on screen.
  • Check to make sure any subtitles are "title safe", i.e they won't be cropped out by the aperture plate. Same goes for changeover cues, make a note if they are very close to the top of the frame, or very low in the frame.

Hard Matte and Open Matte Prints

See Aspect ratio for some examples of hard matted, or soft matte (sometimes referred to as full frame or open matte) prints. Some people refer to the matte as a "mask". So "hard mask" and "hard matte" refer to the same thing.

Hard matted prints have black bars on the top and bottom of the frame. If you are projected a print like this and it comes up put of frame, you will likely see these bars on the screen, making it fairly easy to frame correctly so that they are no longer visible. Soft matte prints do not have these bars at all and the projectionist must frame correctly without them. Follow the guidelines above for framing correctly, but then also pay attention to the image on screen. Look for things like heads being cut off if the framing is too high, lots of space over someone's head or the appearance of boom mics if the framing is too low.

Lab Splices

Aperture plate