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This topic comprises 4 pages: 1 2 3 4
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Author
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Topic: My Big Bulge
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Randy Stankey
Film God
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Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99
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posted 07-24-2002 10:16 AM
Joe,I have seen this occur on many types of platters (Christie, Strong, Speco) and, although it can be caused by too much take up tension, I find that a more likely cause is damaged film. If it's too much tension it will go away once you fix the platter or move it to another. If it's damaged film it will be there forever, no matter what you do. The most common cause is roped edges. (Back here, we call it "Spiked".) Somehow, the film has jumped off a sprocket and the teeth have made indentations in the film. Often this is because one of the pad rollers has become maladjusted but it can also occur because of a bad splice. Either, the holes weren't punched in the tape or there may be a misialigned lab splice that wasn't caught in time. Check the film for "spike marks". Right before the place where they start, I bet you will find said splice. Fail that, it could be a poor threading job or a loose pad roller or intermittent shoe. Since I know you are pretty conscientious, my bet is on a lab splice. Even though I checked for them religiously I have missed one or two of them in my day. Once the film is damaged, there isn't a lot that can be done about it. If it's really bad, you MAY have luck rewinding the film back and forth on the bench under high tension. Mind you this is not a good thing to do in every day practice. I can cause scratching and other "not good" things to happen. However, if it's all you can do to save the show, you could try it. The best solution is to get a new print. If you can't do that, there is a chance that the damage will "play out" after several shows. On the other hand, if it's really bad it will cause progressive damage as the film plays. The telltale is that the film may "buzz" as it plays throught the projector. On occasion, you may find that the film has jumped off the sprocket again even though you have found the cuase and effected a repair. The damaged sprocket holes tend to "lead" the film off-track. Needless to say, no matter what the cause, I would babysit that film pretty closely from now on until you are satisfied that nothing else is going to happen.
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John Pytlak
Film God
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Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000
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posted 07-24-2002 10:33 AM
When a print gets "roped" by sprocket teeth, the little indentations have a slight ridge around them, making one side of the film effectively a bit thicker than the other. Even a tiny thickness difference adds up over hundreds of laps of film in the roll. The same thing can happen if very high tension stretches the film.Sometimes, changing the winding orientation (soundtrack up vs. soundtrack down on the platter) will help. ------------------ John P. Pytlak, Senior Technical Specialist Worldwide Technical Services, Entertainment Imaging Research Labs, Building 69, Room 7525A Rochester, New York, 14650-1922 USA Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243 e-mail: john.pytlak@kodak.com Web site: http://www.kodak.com/go/motion
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Ken McFall
Jedi Master Film Handler
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Posts: 615
From: Haringey, London.
Registered: Apr 2001
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posted 07-24-2002 10:52 AM
This is a problem that I've had in the past, we use Kinoton ST200 platters. It was caused by too tight takeup and resolved by taking some of the tension off the return arm... Problem solved. However at times some prints don't take up as tight as I'd like, so its a trade off. Humidity plays its part too but tension seemed to be the biggets culpret in our case at least. We tend to move prints from screen to screen during the day, Often with three films in a screen each day as well.One way around the problem is to use a large take up ring, the Kinoton rings are great for this as they have a locking arm built in and lock solid. That way if the print does bulge the film is nowhere near the module to cause a problem. With the larger diamameter the plate is running slower so the irregular shape is handled better. The knock on benefit is that its much easier to insert and remove ads and trailers with a larger ring.
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