Film-Tech Forum ARCHIVE: Perforating the other side of a 16mm print

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Posted by John Lasher (Member # 968) on 09-05-2012, 08:51 AM:

Not sure where to post this, this seemed like the best bet.

As an experiment/project for a mathematical thinking class, I intent to make a mobius film loop (take 5-or-so seconds of film in a loop, but give the film a twist at the splice) to determine whether the image will end up reversed left-to-right or flipped top-to-bottom (I think I know the answer, and I have to deliver a 3-page paper describing what's going on mathematically). I have a 16mm print I made, but it's silent on sound stock, so it's only perforated on one side. Is there a way to punch perforations in the other side? If so does anyone in the Philly area have the necessary tool(s), and would be willing to lend them to me for this purpose?

Posted by Matthew McBride (Member # 6598) on 09-05-2012, 09:51 AM:

I'm not sure about the hole punching device, though I'm sure there should be something around that can do it. Possibly some kind of pin register device. However if you need help on the math portion, I can help with that, being a mathematician and all [Wink]

Posted by Jeff Taylor (Member # 443) on 09-05-2012, 09:52 AM:

wouldn't it be simpler to get a hold of a length of 16mm silent double perf stock? Look on ebay. There are tons of old Castle/Official 16mm silent prints listed at very low prices.

Posted by Martin McCaffery (Member # 37) on 09-05-2012, 09:56 AM:

You say you have a 16mm print you made. Does this mean you shot it and brought it to a lab? If so, go have it reprinted on double perf.
On the other hand, if you mean you made the loop out of 16mm print you had sitting around, never mind. I may have some double perf 16mm sitting around if you need some. I know I have some double perf porn that came with our 16mm projector, but you probably don't want to use that in a class [Wink]

Posted by Brad Miller (Member # 2) on 09-05-2012, 12:19 PM:

Let me save you the trouble. The image will be flipped left to right.

Posted by Steve Guttag (Member # 268) on 09-05-2012, 01:00 PM:

Yes Brad...but you NEED TO SHOW YOUR WORK!

You could give it to the typical projectionist for a week or so...it is bound to have perforations all over it...perhaps on the other side too.

I would hate to try it but a 16mm splicer might be able to do it but the perfs are bound to be less than precise and probably proud.

Posted by Monte L Fullmer (Member # 2797) on 09-05-2012, 03:40 PM:

Can you use 35mm film and save the trouble since you're doing the image test anyway?

Posted by Jeff Taylor (Member # 443) on 09-05-2012, 03:56 PM:

I'm sorry I'm at my beach house on Long Island. I've got thousands of feet of miscelaneous double perf 16mm shorts at my NJ house you could have. Seriously, though, ring up 16mm on ebay and you'll find tons of silent double perf stuff like the old Castle News Parades from $5 or so for 400'. I seriously doubt you could hand punch your single perf film satisfactorily even with a decent guillotine splicer.

Posted by Jack Theakston (Member # 4484) on 09-05-2012, 04:53 PM:

What Jeff said.

Posted by Jock Blakley (Member # 6552) on 09-05-2012, 05:37 PM:

And if it had to be your work, Kodak do still make 3383 as 2R.

Posted by Simon Wyss (Member # 6218) on 09-06-2012, 02:24 AM:

Describing what is going on mathematically . . .

Gives me a headache. Can you tell me who would want to know that and for what?

Posted by Matthew McBride (Member # 6598) on 09-06-2012, 09:48 AM:

So Simon, what is going on mathematically, is that a Mobius strip has only one side to it. Like Brad said, when the splice passes through the gate, the image will be flipped and this will happen every time the splice passes. Mathematicians find this object interesting because it is a something that appears to be a three dimensional object but it really is only a two dimensional hence the fact that there is only one side to it. If you picture an ant walking on "one" of the sides, as it walks it will end up on the "other" side, then continue walking it will end up right back where it started. The strip has also important properties in many areas of mathematics. There are some neat calculations that can be done in calculus using these things. One interesting item is the Klein bottle is a similar setup to a Mobius strip. So a Klein bottle a bottle that has no inside or outside which in its own right is a pretty cool object. So a common joke among mathematicians is to drink beer out of a Klein bottle, so there are actual bottles made but they aren't really Klein bottles, and since the bottle has no inside or outside it is impossible to run out of beer. [Smile]

In physics there are many applications because Mobius strips can model certain particles and other sub atomic objects. One use that I was not aware of until recently is that Tesla used these to make resistors that cancel out there own inductive reactance. I was chatting with a physics person about Tesla and that came up. There are many other applications in physics besides the two I listed.

Posted by Simon Wyss (Member # 6218) on 09-08-2012, 03:27 AM:

So kind of you to explain about the Möbius strip but I confess to be not familiar with the mathematician kind of humour, perhaps because I am not in beer (anymore), and confess also that I am with Brad who brought it to the point.

I just wouldn’t understand what can be interesting—mathematically—about a twist in the film. Sorry, I hate maths. And chess.

Posted by Matthew Jaro (Member # 1786) on 09-09-2012, 10:34 PM:

Simon --- What John wanted to know was what was going on mathematically. The fact that math gives you a headache is irrelevant. I don't recall John asking you about headaches. Matthew McBride provided the explanation, which I thought was really good. Don't run him down for doing it. I hope your distaste for mathematics doesn't cause you to get cheated in life because you can't make change or you can't convert measurements.

Posted by Simon Wyss (Member # 6218) on 09-10-2012, 04:38 AM:

Isn’t it rather the other way around, namely that John as a participant of a thinking class is feeling uncomfortable about twisting a snippet of film?

Stricter still he wants to know about perforating film, one of the most secret and least discussed subjects of the industry, and he wants to know whether there might be a perforating service in and around Philadelphia.

Can anybody tell where the perforators are? I was once lucky to find a lab that had an old Debrie punch. The lab is long since closed, the Debrie most probably with an archive. Do you know how much a fresh perforating machine costs? They start at $60,000.

The only 16mm film perf services I know of are with FilmoTec, Wolfen, Germany, and G. H. Films; 62, rue du 42ème de Ligne, 94340 Joinville-le-Pont, France. They have no computer.

http://www.filmotec.de/?page_id=32