Film-Tech Forum ARCHIVE: what are these lines i'm seeing on my screen!?

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Posted by Michael Uebler (Member # 6876) on 05-13-2012, 05:06 PM:

So, just yesturday i was playing 21 jump street which was in scope. I made my first change over and i noticed on my one projector i was seeing several fine virtical lines on the rightmost side of my screen. My first though was that the anodes got out of whack and i was seeing the soundtrack. This prooved to be untrue as when I moved the bulb the lines stayed put, so i put the bulb back where it was. I thought there may be something on my apature plate, I made my change over (no lines on the other projector) 20 minutes go by I changed over again sure enough same lines i figured maybe my scope was dirty or something, but sure enough today during wrath of the titan which is in flat, the lines were back. they're rather opaque and during a dark scene you can't tell they're even there but if it's a light scene it's pretty noticable just these long thin slightly darker then the movie, lines. Any suggestions anyone?

Posted by Kenneth Wuepper (Member # 1174) on 05-13-2012, 05:29 PM:

Hello Michael,

You are experiencing the symptoms of a scratched print. The dark tone of the scratches would indicate that they are on the base side of the film as opposed to the emulsion (imaged) side where the abrasions have different colors depending on the depth of the scratches.

The image in the gate of the projector is upside down and reversed from left to right. So, if you are seeing the scratches on the right side of the screen, the film is scratched on the edge closer to the gears and away from the sound track.

Often this type of scratch results from a frozen guide roller above one of the sprockets. If the scratching continues to get worse, you are causing it to happen.

If you have an old (unscratched) trailer from which you can make a loop of film and run it for some time (the light need not be used for this test) you can see if any scratches appear on that film.

We often receive films that are similarly scratched throughout the entire length of the feature.

Good luck and happy hunting for the cause of the problem.
.

Posted by Robert E. Allen (Member # 1351) on 05-13-2012, 10:44 PM:

I concur with Ken. Your equipment is causing the problem.

Posted by Randy Stankey (Member # 64) on 05-14-2012, 12:18 AM:

It could be caused a piece of crud or a burr in the film path, too.

Check the trap, aperture plate and sound head for cleanliness and for things that could scratch the film.

One time, I had a tiny piece of glass that cracked off the sound head door and fell between two rollers and rode against the film, scratching the living hell out of the entire movie. It was impossible to spot until the next time the movie was run because it occurred after the film had been projected. It wasn't until we scoured the entire projector for problems and found the piece of glass lying in the bottom of the projector when we found what had happened.

There was one operator who had the habit of slamming the sound head door shut, causing the glass in the door to crack and shed little pieces of glass into the projector path.

This probably isn't the cause of your problem but I tell the story because it illustrates the idea that little things can become big problems unless you are on the lookout for them.

The character of the scratch can tell you where to look for the problem. A squiggly scratch versus a straight "pencil line" scratch might indicate that the film is rubbing against the projector bulkhead or that something is broken, maladjusted or out of line with where it should be.

You would probably do well to have somebody go through the film path of both projectors, give everything a good cleaning and check for problems.

If you could tell us the model of the projector, it would help us narrow down the source of the problem.

Posted by Michael Uebler (Member # 6876) on 05-14-2012, 01:32 AM:

Thank you guys I'm taking everything everyone said and taking it all into consideration, and not ruling out any possibilities.

First off I run on two simplex XL's pr-1003 and pr-1004

I plan on going in on wednesday and taking Ken's advice and putting on a few old previews i still have around and give the machines a full overview and cleaning of a lifetime. I all ready have daily and weekly cleaning that i do, but the other projectionists more like the guys who used to show movies at my theatre left it in pretty bad shape, i'm doing my best but i still have a laundry list to do before everything is running perfect.

I really appreciate everyones opinion, this website and some mentouring from my boss at the black river drive inn (who is in the process of going digital) is really my only form of reference. Thanks again guys i'll be sure to post what happend on wednesday and hopefully i won't have a story like randy's

Posted by Monte L Fullmer (Member # 2797) on 05-15-2012, 06:56 PM:

Since you have older XL units (prob the black wrinkle cased units), these units contains the older "shouldered pad rollers", which are the rollers that holds the film on the sprockets, esp the two rollers for the middle constant speed sprocket which is the sprocket after the intermittent sprocket.

If you look at one of the rollers, there is an inner 'shoulder' that is supposed to keep the film aligned with the teeth on the sprocket while the film is travelling on the sprocket.

What happens is the lower loop gets built just a bit too small and the film that enters into between the roller and sprocket and from a small built loop, the shoulders are actually scratching the base side of the film next to the sprocket holes since the film is entering this confined space between roller and sprocket on the high side and the first surface that the film contacts is these shoulders, and eventually you see this mirad of heavy scratches on each side of the picture on the screen.

You either have to build your lower loop a bit more bigger-like two sprockets worth, or replace the rollers to non-shouldered rollers.