|
|
Author
|
Topic: Static problems?
|
Joe Redifer
You need a beating today
Posts: 12859
From: Denver, Colorado
Registered: May 99
|
posted 08-04-1999 05:46 PM
Lately I have been having at my theatre what appears to be static problems, but I am not entirely sure. The symptoms are exactly that of a static infested print: erratic feed-out and the tail comes untucked. However I have noticed this only on the last reel or two of a given print. A single pass of FilmGuard will cure this, but I have found some other interesting "cures" as well. The first thing I tried was to wrap what I like to call a "filmbelt" around the print, which eliminates the tail tuck altogether. The filmbelt is a piece of film (I use blank film that has been 'erased' and can be obtained from Kodak... at least that's what the film itself says) that is taped to itself and stays on the platter deck as the film ends. It can then be slid over the top of the print easilly for the next show. When I use this, sometimes the static seems to go away altogether for some reason, as if the tail tuck was causing the erratic feedout (I wouldn't be surprised if it were). Sometimes the tuck can interfere as the film is being pulled toward the brain, as the film must be pulled over the tail and can, in my experience, initiate improper feed. This will cause the print to slide all over, the print will become misshapen, and the tail to become untucked. Not good. The filmbelt will prevent the tuck from initiating any problems. If the tuck itself is not the problem, then the filmbelt will prevent the film from sliding all over the platter (in my experience). I do not ever recommend suction cups as they are pretty much worthless, and the filmbelt does a much better job. If you insist on using suction cups, then I recommend TECO pucks, which are quicker and easier to use, and far more effective in my opinion. A friend of mine at a different theatre that also uses Christie platters will put a small trailer core in the brain after the first reel has passed. This will prevent the brain from reaching 100% and throwing the print. This should be done if the platter is not timed properly. He uses this in combination with the filmbelt. I find that if you time your platters properly, you do not need to do this. But if you feel that your platter is not timed properly and "bursts" to full speed when slowly moving the throttle from 0% to 100%, then you may want to give this a try.
| IP: Logged
|
|
|
|
|
|
John Pytlak
Film God
Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000
|
posted 01-29-2002 05:55 AM
Mathew Molloy said: "Anyway, I did find out that if I go up and let the edge of a long screwdriver glide along the edge of the last reels for a couple seconds the static goes away!"Sounds like the print has no path to ground through the platter, so static is able to build up. Touching the film edge with the screwdriver is providing a path to ground, allowing the static to discharge. Even though the print film has a conductive backside layer, the static must have a path to ground, or it can build up and cause inter-layer sticking. You should definitely be sure the platter surface is clean and free of non-conductive oxide buildup. Be sure the platter frame is well grounded. Treat the surface of the platter and any rollers with a conductive antistat like Static Guard or Endust for Electronics. There are also conductive brushes on the market that gently contact the film while running to assure a path to ground for any static buildup: Kinetronics Anti-Static Brushes The last reels of longer movies tend to have the most problems with "static cling", since the film is pulling away at such a shallow angle as the feed point gets further from the center. That is why longer movies like "Ali" and "Lord of the Rings" seem to have more static problems. Additional things to try are measuring and maintaining the proper relative humidity (50 to 60 percent RH is best), winding the film with the opposite orientation (so the natural curl of the film helps resist pulling-in), checking platter timing and leveling, and better restraining of the outside of the roll to prevent sliding and "static fling". ------------------ John P. Pytlak, Senior Technical Specialist Worldwide Technical Services, Entertainment Imaging Research Labs, Building 69, Room 7525A Rochester, New York, 14650-1922 USA Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243 E-Mail: john.pytlak@kodak.com Web site: http://www.kodak.com/go/motion
| IP: Logged
|
|
|
|
|
All times are Central (GMT -6:00)
|
|
Powered by Infopop Corporation
UBB.classicTM
6.3.1.2
The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion
and agrees to release the authors from any and all liability.
|