Film-Tech Forum ARCHIVE: 16mm print jittery

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Posted by James Collins (Member # 7565) on 10-17-2013, 07:57 PM:

Hello,

I recently bought an ib technicolor print of dumbo. I previewed the picture on my projector. And the print jumps around a bit.

I tested another print on my projector and it is rock steady.

So I am wondering what would cause a print to jitter, and is there anything I can do to stabilize the image?

Posted by Matthew McBride (Member # 6598) on 10-17-2013, 10:37 PM:

The print could be warped or have vinegar syndrome? What film stock is it on, polyester?, tri-acetate? Does it have a vinegar odor to it? You can try FilmGuard to make the film more flexible so it can run through the gate easier. If you can tell us more about the print itself, a more pinpoint answer can be given.

Posted by James Collins (Member # 7565) on 10-17-2013, 10:58 PM:

No vinegar smell

Posted by Frank Angel (Member # 248) on 10-17-2013, 11:26 PM:

What about the sprocket holes -- look really close with a loupe i.e., a magnifying glass, and see if there are any very small nicks in the side walls, usually at the corners. If there are, the only thing you can do is try Film-Guard which as said will give the print more elasticity as well as reduce friction for a smoother run. Then again, is your projector a portable with claw pulldown? Is it a two or three claw pulldown mechanism? Sometimes a combination of a worn claw playing a print with compromised sprocket hole walls will translate to jitter on the screen. Then again, you could try a 16mm projector with a sprocket drive intermittent -- an Eastman 25B 16mm projector could play prints with ease that had two and three sprocket holes totally torn away. Some projectors are hard on prints, some are much more gentle.

Singer turned their sewing machines into 16mm projectors -- same claw pull-down concept and mechanism, but their 16mm projectors always sounded exactly like their sewing machines and played prints in similar, agressive fashion -- their slogan could have been, Play a movie...Darn your socks on the same machine! [Big Grin]

Posted by James Collins (Member # 7565) on 10-18-2013, 09:13 AM:

Reran print on an old eiki, runs good?

Posted by Manny Knowles (Member # 1171) on 10-18-2013, 11:28 AM:

Could it be something as simple as adjusting gate tension?

Posted by Scott Norwood (Member # 30) on 10-18-2013, 01:00 PM:

Is the problem one of jump (vertical unsteadiness) or weave (horizontal unsteadiness)?

The whole print does this (all reels)? And other prints run fine in the same projector, correct?

What happens if you show the IB print on another projector?

If the issue is jump (not weave), then my bet is on gate tension, although adjusting this is easier said than done on most 16mm projectors.

Are there any obvious physical problems with the print (torn sprockets, etc.)?

Posted by Jeff Taylor (Member # 443) on 10-18-2013, 01:18 PM:

Singer/Telex projectors do have adjustable gate tension. For the others, it's a question of gently extending the pressure plate springs until you get what you need. Of course, that's a "one way" proposition. You can't go back unless you start cutting the length of the springs.

Posted by Randy Stankey (Member # 64) on 10-18-2013, 03:51 PM:

My first plan of action in troubleshooting any projector that has been acting up is to clean it.

That doesn't necessarily imply that your projector is dirty but, in the act of cleaning, you'll have the opportunity to inspect, adjust and repair anything that needs it. Besides, it's a lot easier to work on a clean projector.

I don't know how many problems I have had which were solved just by giving the machine a good going over. So much so that, when a theater would call me with a vague problem like "unsteady image" or "fuzzy picture" my first response was to tell them to clean the projector and call me back.

With a 16mm, I'd say that cleanliness is even more important because everything is so much smaller.

Again, I'm not insinuating that your projector is dirty but I bet you a nickel that a good going over might help solve your problem or give you a good lead on what the problem really is.

Posted by Gary A. Hoselton (Member # 3447) on 10-18-2013, 10:48 PM:

Usual reasons for vertical jump in 16mm projector are:
1. Film too slick. Pull-down momentum is absorbed by friction in gate, and slickness means not enough friction. Get slickness by some dolt applying silicones or too much fresh FilmGuard. With pencil eraser, push top of pressure plate lightly against film to increase friction and see if film settles down; if so probably need to thoroughly clean print.
2. Variable perf distortion on forward edge.
3. Excess filmbase shrinkage, such that shuttle teeth may tick next perf.
4. Printing problem, but I don't recall that in IB Tech (sometimes horizontal weave, but not vertical jump).
5. Wear on shuttle teeth or in intermittant, but you've eliminated that because another print runs fine. A new or "green" print can have too much friction, but no IB Tech is likely in that catagory.
Let us know what you conclude.

Posted by Jeff Missinne (Member # 8039) on 12-31-2013, 07:21 PM:

Right about how a 16mm print can be too slick as well as dry or sticky. I used to hate handling prints treated with Filmagic Surfaset for that reason...awful stuff.

The old quick-dry film cleaners like Kodak or Ecco were great for removing silicone slickery, but they don't make 'em any more. Haven't tried Solvon, but a friend likes it very well.

I once cleaned a cartoon short over and over to try to eliminate a vertical bounce...then accidentally ran it out of frame and found the jitter was in the negative! [Embarrassed]

Posted by Brent Francis (Member # 5008) on 01-01-2014, 08:10 AM:

That's an idea - rack it down & check the frameline. Is the picture moving & the frame steady? Then it ain't you!