Film-Tech Forum ARCHIVE: twists in film

This is topic twists in film in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Andrew Vanderhoek (Member # 2648) on 09-10-2004, 12:02 PM:

Recently I got into an argument with one of the managers about threading a projector. The first thing that we are disputing is the sound bar. When threading the projector the sound bar should always be facing up on the platter. Is there a reason for this or is it just standard, the manager says that it does not make a difference.

The second argument is twists in the film. I know when threading a project you should not have any twists in the film especially where it loads onto the platter because you can get platter scratches. If you do have a twist in the film anywhere while threading the projector will this cause any problems while the projector is running or is it ok to do that?

Posted by John Pytlak (Member # 331) on 09-10-2004, 12:48 PM:

It's all covered in the Film-Tech "Tips" section under "Threading 101":

http://www.film-tech.com/tips/threading.html

"Finally, bring the film to the "catch" on the center ring. Again, make absolutely sure the soundtrack edge of the film is pointing toward the tree at this final roller and is twisted UP, away from the platter's surface."

For old triacetate prints on reels or cores with small hubs, SMPTE Recommended Practice RP39 specified the film always be maintained in an emulsion-in orientation to improve focus stability and reduce "focus flutter". But for modern polyester prints on platters, there are advantages to keeping the analog soundtrack up and away from the platter surface.

Note, if you have a hopefully rare occurance of "static cling", changing the winding orientation sometimes helps, depending on the humidity curl of the film. As the relative humidity becomes very low, the gelatin emulsion shrinks somewhat, giving the film more "positive" curl; very damp conditions may make the film curl in the other direction as the damp gelatin expands ("negative" curl).

Posted by Dustin Mitchell (Member # 372) on 09-10-2004, 12:51 PM:

Soundtrack up is because estar based film stock has a natural curl too it. Winding it soundtrack down will stretch the curl and cause focus problems in the print.

At least that's what I've been told. Never experimented with it myself (for obvious reasons). Doing it one way or the other is good standard practice though, and with the above statement soundtrack up seems to win the day.

Generally one twist per 'run' between rollers is not too bad so long as the rollers are far enough apart. A twist in the film between the take-up roller on the edge of the deck and the center ring would not be okay though, for the reasons you mention.

Honestly, if you thread the same way every time you should never have any twists.

Posted by Robert L. Fischer (Member # 2424) on 09-10-2004, 06:51 PM:

I've started a movie before that had a single twist in its longest path between the platter tree and the projector, but that was when someone else threaded it and apparently messed something up (perhaps threaded the projector soundtrack in and fixed it). I wouldn't start anything with more than one twist and I wouldn't start anything with a twist anywhere other than a path that's at least 5 feet or so long. Correct me if I'm wrong, but I don't see where one twist in 5-10 feet of film could do any significant damage to the film. I'm sure there's some added risk of something going wrong while the movie is running though.

Posted by Jacob Szewczyk (Member # 2513) on 09-10-2004, 08:00 PM:

We thread it with the soundtrack facing down and we have had no problems with it. Also, we usually have, at most, one twist, and is eaither from the roller right under the projector to the platter, or from the first platter roller to the yolk on take up.

Posted by Randy Stankey (Member # 64) on 09-10-2004, 09:03 PM:

Questions about what's better for the film aside, you should come to an agreement exactly how the film is to be threaded through the system... roller by roller... turn by turn... and have EVERYBODY stick to that pattern EXACTLY.

Why? There are several good reasons.

If one person threads the projector one way and the next person does it his own way, if there is a problem, you might find yourself in a position of having to decode somebody else's threading pattern before you try to solve the problem. It will prevent you from being in a situation like, "Randy threaded this projector. He puts this funky twist in the film right after it comes out of the payout control. Every time I have to fix one of his screw-ups, I have to go back and fix that damn twist before I can solve the real problem."

It will prevent film damage. Assuming you have worked out a threading pattern that makes it impossible (or difficult) to damage film, if everybody sticks to the plan, no film should ever get damaged. Putting a twist or a turn in the film in just the right (wrong) spot could mean the difference between the film running correctly on a roller and jumping off or riding up a flange or something worse.

If there IS film damage... ostensibly from a malfunction of some kind... it will be easier to figure out what the cause is. You sould be able to look at the film and deduce which rollers, sprockets or pads are responsible for the problem.

Finally, let's imagine that film is getting scratched on the left side of the picture because there's a burr on a roller somewhere. If the film is threaded a different way each time, you might end up with scratches all over the film because a different part of the film rubs across that burr each time the film is threaded. Before you know it, you'll have scratches running down BOTH sides of the picture! It'd be like throwing salt on an open wound!

You, your manager and your technician should sit down and have a discussion about what's the best way to thread your particular setup. Once that's been decided, everybody should be trained in how to thread that way and ONLY that way! After a suitable period of time for people to get used to the new way, anybody who fails to follow the pattern should be subhect to appropriate disciplinary measures.

Posted by Peter Mork (Member # 1336) on 09-11-2004, 01:49 AM:

Soundtrack up or down? It really doesn't matter, but everyone in the booth should do it the same way. And as the film winds onto the platter, the bottom edge should lead such that it doesn't "fight" the rotation of the platter, if only to prevent an annoying scraping sound.

Everyone develops their own routine over time, and in most cases there's no absolute "right" way to do a film path, so unless someone's consistiently putting severe twists in the film, I see no reason to cramp someone else's style just because it's different from yours. It's more important to maintain your roller alignment such that film won't get scratched no matter how it's threaded.

Posted by Brad Miller (Member # 2) on 09-11-2004, 02:43 AM:

I'm mostly with Randy on this one...inparticularly if you are doing something out of the norm like we do with the platter array. Everyone simply MUST thread every twist and turn the same way, because in our case should a scratch turn up, there are literally dozens of different ways the film could have been threaded and it would make tracking down the cause next to impossible. (Of course we don't screw up in the first place, but that's another topic. [Wink]

)

With that being said, we thread with the emulsion on all of the rollers, except where it would force a ridiculous twist (such as the three roller cluster on takeup (AW3 platters), the first takeoff roller on the tree and the two takeup rollers on the wall in front of the projector. Other than those exceptions, the rest of the rollers in the system are "emulsion side" threading. After all, it's the base side that carries the dirt.

Always run soundtrack up and always keep the soundtrack toward the tree on takeup. (There are a few exceptions where the soundtrack should run away from the tree on payout, such as a SPECO.) Running soundtrack down exaggerates the curl on the film which causes some minor focusing issues (most noticeable on polyester prints, of which all are these days). Also, the film will physically run louder through the projector due to the exaggerated curl, and some projectors simply cannot run heavily curled film without producing an abnormally shaky image. These threading guidelines also help to minimize foolish operator mistakes. For example, let's say you have a Strong/SPECO platter with a takeup elevator. By keeping the soundtrack up on the platter and toward the tree, should the film come off of one of the takeup rollers and ride on the roller shaft, you will only have black base side scratches instead of beautiful colored emulsion scratches. Same thing goes for running soundtrack up in terms of diagonal scratches. Those are caused by lousy platter designs which run the film too close to the platter deck. Even if nothing I've written here is good enough for someone in the midset of "but this is how I have always done it" to run their films soundtrack edge up, you can't argue with the fact that running soundtrack up protects the emulsion on the wind from diagonal scratches! (I haven't seen a theater in an awful long time actually run soundtrack down, but there are undoubtedly some lingering Cinemarks out there still running that way thanks to one doofus trainer they used to employ.)

Another thing to look at is the twisting of the film into and out of the projector. If your platters are on the non-operator side, the soundtrack should run away from the screen to and from the platter. (See this in "Threading 101") If your platters are operator side, the soundtrack should run toward the screen as the film travels to the projector regardless of the platter's tree orientation. In regards to takeup on an operator side positioned platter, if your platter tree is aimed at the projector, the soundtrack should run toward the screen on takeup. If the platter tree is square to the theater wall, the soundtrack should run away from the screen on takeup (forcing a half twist during threading). These guidelines minimizes the amount of twist put on the film as well as maximise the amount of rollers that the emulsion will ride on, keeping your films cleaner.

Posted by Peter Mork (Member # 1336) on 09-11-2004, 04:04 PM:

Most booths do go with "soundtrack up", as a convention. But I seriously doubt doing it otherwise would lead to any kind of focusing problem, in the real world. Film does have a natural curl, but I need to see experimental data before concluding that winding it one way or the other on a big diameter platter core will make a dime's worth of difference in whether that curl is exaggerated or lessened depending on how you do it.

Posted by Brad Miller (Member # 2) on 09-11-2004, 05:04 PM:

I've done the experiments Peter and it's there, otherwise I would not have spent the time to write out my above post. To any non-believers out there, do your own tests to prove it to yourself. [Smile]

Posted by Steve Guttag (Member # 268) on 09-11-2004, 10:14 PM:

I've done the tests myself...emusion-IN has always won on focus stability for me...tests have been limited to the mid-atlantic area. This has been done for reel-to-reel and platter operations.

For platter operations I have not found that the orientation made a lick of difference to focus.

However, emulsion out (track up) does benefit the platter operation in other areas. With emulsion out wind, the base is presented to the feed-fingers and guide posts as well as the spinning take up deck. Any rubbing on these parts will not rub away or otherwise damage the SDDS track nor likely to cause emulsion scratched in the event of other disasters. As such, I run track up on platters but emulsion-in on reels (upper and lower, no "S" wind).

Clearly, your results may vary but those are mine.

Steve

Posted by Brad Miller (Member # 2) on 09-11-2004, 11:51 PM:

That's a misleading post there about reel to reel operation, Steve. You told me you have never tested running emulsion out operation with polyester film. Unless you have done thourough testing with this, your comment above really shouldn't be taken too seriously.

Posted by Tommie Evans (Member # 2674) on 09-12-2004, 08:10 AM:

Has any one come across problems with prints after running them on a Christie platter (AW3) and then moving the print to a cinemeccanica platter (CNR3-35N).

We have four AW3 screens and 21 CNR3-35N screens (dont ask! [Eek!]

)
As a print finishes on the AW3 and is moved onto a CNR3-35N the print will completely fold-in on itself, collapsing after the first show. This happens regardless of twists or sound-track 'up' or 'down' resulting in the film almost crushing the pay-out unit.

I'm guessing that the cinemeccanica platter loads to film onto the platter fairly tight, where as the christie takes-up fairly loosely. Is this problem caused by the tightness or the different film roll diameter as it loads onto a different size take-up ring, or is it a static problem???? [Confused]

Posted by Steve Guttag (Member # 268) on 09-12-2004, 12:25 PM:

Nope...not misleading...the emulsion-out tests were S-winds but stored heads-out emulsion-out....emulsion-in was always the more stable....however...if an emulsion out wind occurs...it can take weeks for the emulsion-in benefit to come back. Emulsion-in, with polyester or acetate remains the most stable for reel-to-reel.

Steve

Posted by Peter Mork (Member # 1336) on 09-12-2004, 01:06 PM:

quote: Brad Miller
To any non-believers out there, do your own tests to prove it to yourself.

Well, being the skeptical sort, I can't resist picking up the gauntlet and doing the following experiment.

I took about 30 feet from a recently-struck print (an incomplete reel of Hero we got sent, a sad story in itself). Did a "pinch test" - dangled the film vertically and pinched the edges to see which way it wanted to bend. It curled emulsion-inward, as expected.

Cut it at the midpoint, flipped one half over, and spliced together. Wound it snugly around a standard Super Platter centerpiece, taped down the end, and set aside. Will check it in a month to see if curl, or more importantly projected focus, is affected between the track-up and track-down sections.

Watch this space for the thrilling, and no doubt utterly inconclusive, result.

Posted by Brad Miller (Member # 2) on 09-12-2004, 01:54 PM:

Yes Steve, misleading...because you never gave emulsion out exclusitivity AND you never tried it with polyester. Again, you confessed to this before in the chat room.

Posted by Steve Guttag (Member # 268) on 09-12-2004, 02:17 PM:

Not misleading Brad...I have checked on emulsion out winding though not exclusivity except on platters...whereas emulsion-in winding was definately superior to S-winds with emulsion out storage. Like you, I'm constantly checking on improving projection methods. If I saw emulsion out winding on reels to improve the show, I'd be all for it...I've only seen the contrary. With platters I used to run track-down...I prefer track up now and that did switch around polyester time...less problems and less damage overall.

The fact comes back to...regardless of base curl....with emulsion-in wind, you are placing the emulsion in a relaxed state and then stretching it for projection...emulsion out winding you are stretching the emulsion and then hoping to have it compress evenly on projection...particulalry on the inner wraps of a reel...again, it is not the same issue with platters were even the smallest rings are around 10-inches.

Steve

Posted by Brad Miller (Member # 2) on 09-12-2004, 02:38 PM:

If only every print on reels that was wound emulsion in I have handled wasn't stretched, twisted and curled, I might be able to buy that.

You still need to do some exclusive emulsion out winding on polyester though. Even back in the day when I would wind film emulsion in on an S wind, the film doesn't seem to like being constantly flipped back and forth between winding orientation. Indeed exclusive emulsion in is better than an S wind, but moreso exclusive emulsion out is better than exclusive emulsion in, and with that...your post is still misleading because you haven't really tried it yet. [Razz]

Posted by Steve Guttag (Member # 268) on 09-12-2004, 02:58 PM:

Brad, the vast majority of the time (greater than 99%) of an S-wind's life is in the emulsion-out orientation...only for the breif period after projection but before rewinding is it in the emulsion-in orientation.

In your platter threading recommendations, you recommend that the emulsion be towards the rollers (with a few exceptions due to sillienss in threading)...this would put the emulsion in a "flipping" situation yet you don't find it detremental there...why? Because it is brief.

Steve

Posted by Brad Miller (Member # 2) on 09-12-2004, 03:07 PM:

Yes Steve, it would be just as brief as having the film make various turns inside a projector. Also, not everyone rewinds the film immediately after projection. Most changeover booths I have worked the reels were stored tails out (against what seemed like common sense to me). Still, I will say it again, until such time as you have tested exclusive emulsion out on reels, you really cannot make such claims. Should I repeat it another time?

Posted by Steve Guttag (Member # 268) on 09-12-2004, 04:49 PM:

Sure go ahead...if it makes you feel better. Emulsion-In on reels still wins hands down for me. It doesn't bother me in the least that you have found different results in Texas.

Steve

Posted by Brad Miller (Member # 2) on 09-12-2004, 04:55 PM:

I haven't found different results, you haven't tested emulsion out.

This really would be like me saying "a Smart Mod 5 sounds much better than a Panastereo". Well, I haven't heard a Panastereo yet, so how can I claim that??? Same thing Mr. Steve.

Posted by Steve Guttag (Member # 268) on 09-12-2004, 05:23 PM:

The films I've looked at with emulsion out wind only have them emulsion-in for the brief period the film was on the take up reel (less than 1-hour per show...often less than 20-minutes...is your claim that amount of time sets up the problem? All of set ups evaluated store their film in the rewound state, emulsion-out...I don't buy your "haven't tested it yet" claim.

Steve

Posted by Gordon McLeod (Member # 33) on 09-12-2004, 05:46 PM:

I have always found emulsion in is the best
even with polester stock
At the old albion theatre we had in the large house two vic10's who's payout clutch was a ratchet design and it would only turn counter clockwise in the smaller theatre the vic8's would turn either direction
so they ran clockwise
both had 4K xebex lamphouses on them and the emulsion in always had less focus issues
When a platter (ORC) was installed that same orientation was followed on each screen and the focus was always more stable emulsion in

Posted by Brad Miller (Member # 2) on 09-12-2004, 06:08 PM:

Steve, I am saying...again...that I agree with you on this...
Exclusive emulsion in is better than S winding.

However I am also telling you this based upon my findings...
Exclusive emulsion out is better than exclusive emulsion in.

You're a smart guy. Why don't you understand what I am saying? The fact of the matter is you have never tried winding exclusive emulsion out on reels, so you have no business claiming that one way is better until such time that you have done reasonable testing. If you still don't get it, I'll get others to reword it until the time comes you get my point.

Posted by Peter Mork (Member # 1336) on 10-15-2004, 12:11 AM:

Test results are in (see my last post on first page).

After 30 days, film wound on a platter soundtrack-up and down (or emulsion-out and in, if you will): both ways still curl emulsion inward when pinched.
Ran film on Brenkert, Century and Simplex projectors. No visible difference in focus between the two sections.

Conclusion: Wind it either way - matters not.

Posted by David Favel (Member # 1125) on 10-15-2004, 07:19 PM:

quote: Tommie Evans
I'm guessing that the cinemeccanica platter loads to film onto the platter fairly tight, where as the christie takes-up fairly loosely.

Actually I find the reverse.