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JITTERINESS - Have you suffered it?


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#1 Terry Mester

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Posted 13 July 2008 - 02:04 AM

JITTERINESS - Have you suffered it?

I'm interested to know if you've suffered jitteriness in the 35mm Camera format. This is a problem that has been associated with the Super8 and Super16 formats, but I know it must exist to some degree in 35mm. Several months ago I was watching the old Sir Richard Burton Movie "Anne of the Thousand Days" which suffered noticeable jitteriness throughout the whole Movie. Since the jitteriness only affected one Camera Shot in the various scenes, I know it wasn't caused by the Projector or Telecine. I have determined a cause of jitteriness in the Super 8mm format that is not related to its use of only one Sprocket Hole. The main problem of jitteriness is caused by a tight Clutch for the Take-up Reel. This problem would affect 35mm & 65mm Cameras just as it affects Super8. In a Movie Camera (and Projector), the Take-up Reel regularly runs out of slack Film as it reels in the used Film coming down from the Film Gate. Every time the Take-up Reel runs out of slack Film, the Clutch on the Camera turning the Reel has to slip until more Film is pushed down by the Film Gate's Sprocket Arms / Claws. However, if the Clutch slippage is too tight, the Film will be tugged by the Take-up Reel -- thus pulling the Film in the Film Gate and causing a jittery picture! The Take-up Reel is only supposed to wind up the Film as it enters the Take-up Chamber. It is only the Sprocket Arms which are supposed to move the Film through the Film Gate -- one Frame at a time. In addition to jitteriness, a tight Clutch will also put a strain on the Camera's Gears and Motor causing it to slow down. If the Camera uses one Motor for both the Clutch and Film Gate, this strain will screw up the Film timing! This strain can also cause a Film Jam. This strain on the Camera's Gears can and will cause wear and even damage.

It is very easy to test the slippage strength of the Camera's Clutch. You test it with the Camera ON. Just stop the Clutch with your finger as it turns, and note how much force is required to stop it from turning. It should slip with only a little bit more force than is required to turn the Take-up Reel. In order to appreciate the small force required to turn the Take-up Reel, with the Camera OFF use your finger to turn it from the center -- not from the outer edge which is easier due to leverage. You will quickly and easily determine how little force is required to turn the Reel before the Camera's Clutch needs to slip. It's a small amount of force.

To verify if the Clutch is too tight and is tugging on the Film in the Film Gate, just load a couple of feet of old Film in the Camera from the Take-up Reel into the Film Gate. Cut out the Sprocket Holes from the Film in the Gate so that the Sprocket Arms cannot catch the Film. With the door open, turn on the Camera, and note the Film to see if it's getting pulled by the Take-up Reel. The Film in the Gate should not move whatsoever. If it's pulled down any amount, then the Clutch is too tight. The Thread Link below shows some pictures of a couple of Super8 Camera Clutches. 35mm Clutches should be reasonably similar in nature.
http://www.cinematog...showtopic=32243

In addition to not tugging on the Film, the Clutch when slipping should not in any way slow down the Camera's Gears! With the cover removed you can verify whether or not the Gears slow down when you stop the Clutch with your finger. Even if the Clutch doesn't tug on the Film, if it causes the Gears to slow down when slipping it is still too tight! This is important for maintaining the Camera's "Timing" in addition to preventing jamming and wear of the Gears.

I personally believe that the concerns about using Polyester ESTAR Film as regards jamming are grotesquely overblown. I assume that a 35mm Camera has an Indicator Light (as in my Super8 Camera) to tell you that the Take-up Reel is turning. You should notice within a few seconds if the Indicator Light stops flashing. I cannot imagine that a Camera would be damaged by being jammed for less than 15 seconds, and it should only take you a few seconds to turn off the Camera if it jams. If the Camera's Clutch is not too tight, then you shouldn't suffer jamming. Given the superior long-term quality of Polyester over Acetate Film, I would strongly recommend to all cinematographers to only use Polyester Films.

If you've suffered jitteriness in the 35mm format, please identify which Model and Year of Camera.
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#2 Sam Wells

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Posted 13 July 2008 - 09:59 AM

JITTERINESS - Have you suffered it?

I'm interested to know if you've suffered jitteriness in the 35mm Camera format.


I've occasionally suffered from jitteriness in all film and many video formats.

Gotta cut back on that coffee or espresso :blink:

-Sam
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