|
This topic comprises 2 pages: 1 2
|
Author
|
Topic: "Extreme" out of frame lab splices
|
|
|
|
|
|
|
|
|
Stephen Furley
Film God
![](http://www.film-tech.com/ubbmembers/1277b.jpg)
Posts: 3059
From: Coulsdon, Croydon, England
Registered: May 2002
|
posted 01-21-2007 03:41 AM
quote: Dustin Mitchell Aren't lab splices made before the stock is processed so there aren't any framelines? I'm pretty sure its impossible to make an out of frame lab splice.
The only way I can see that it could happen would be if the print stock slipped a perf as it went round the printing sprocket. I've never seen a modern high-speed printer, but on an older slow continuous printer the printing exposure takes place at a slit as the negative and print stocks pass around a large sprocket, about four inches in diameter; I've never measured one, and it's a long time since I've seen one, but it's about that size. This means that there would be a large number of perforations on the teeth at any time, so I would have thought that for the stock to slip a perf would be unlikely. Unless of course the high-speed printers are designed differently.
The diameter of the printing sprocket was fixed by the need for the perforation pitch to be slightly longer on the negative than on the raw print stock due to it having a slightly longer path because of the negative between it and the sprocket. The size of the sprocket was chosen such that the shrinkage of the nitrate negative when processed provided just the required difference. When triacetate stock was introduced, which had much less shrinkage, short pitch perforations were needed in the negative, so that it could be printed on the standard size sprocket.
An interesting question arises at this point. Most polyester stock is thinner than triacetate, but if the thickness of the negative is changed on a continuous printer then the diameter of the print stock on the sprocket would be slightly different, and the pitch would be slightly wrong. Are intermediate stocks still made to the same thickness as triacetate ones for this reason, or is the difference so small as to not matter?
| IP: Logged
|
|
Leo Enticknap
Film God
![](http://www.film-tech.com/ubbmembers/534a.jpg)
Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000
|
posted 01-21-2007 05:25 AM
For bulk release printing, stock is usually supplied to the labs in 6,000 foot lengths. In some setups a loop cabinet in front of the printer enables the feed from the outgoing reel to be stopped while printing continues, so that the head of the incoming reel can be spliced to the tail of the outgoing one. In others printing is stopped while this is done. I believe that it is during the stop/start process that the print stock can be pushed out of rack from the internegative - someone did explain the mechanics of it to me once, but I've now forgotten.
Stephen: all the internegative stocks I know of are acetate (Kodak 5272 being the most widespread, I'd guess). Typically, only IPs and release prints are poly. Despite the preserveation issues with triacetate, it is still the base of choice for camera negatives and IPs, because a polyester jam in a camera would cause seriously expensive damage to a very delicate mechanism; and likewise, a jam in a high speed printer could knacker a lot of very expensive print stock. The IPs I've handled don't appear to be any thinner than a typical acetate element (they didn't feel so, at any rate), so I presume you're right and that the difference is so small as to not matter.
| IP: Logged
|
|
|
|
|
|
|
|
All times are Central (GMT -6:00)
|
This topic comprises 2 pages: 1 2
|
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.
|