Talk:Film perforations

Detail from 35mm film

This article needs to get some of the detail about perforation types from the 35mm film article. I suppose I'm biased, since I fleshed out the section on perfs there, but I don't really think what's in 35mm film should be reduced. It's sort of embarrassing, for instance, that the string "KS1870" doesn't appear in this article. Jhawkinson 01:15, 9 March 2007 (UTC)

The article discusses the aspects of film perforations. I don't expect it to carry Kodak's catalog identifiers anymore than I expect the number 5218 to show up in the 35 mm film article. I've also deleted the redundant pitch information which was added to the shape sections. The article should to clarify what the characteristics are, not every possible permutation. Girolamo Savonarola 23:13, 10 March 2007 (UTC)

I think that's a step in the wrong direction. Again, this article should have at least as much detail on this as 35mm film, and hopefully more (otherwise it should get deleted). KS1870 isn't a catalog number, it's the standard notation for type-of-perf and pitch-of-perf. Since it's both used in common (well, somewhat) parlance, as well as referenced in other Wikipedia articles, I think it needs to be defined in this article. I wouldn't expect the '218 to be discussed in 35mm film, but it is (and should be) discussed in List of motion picture film stocks. jhawkinson 23:45, 10 March 2007 (UTC)

Yes, the spec is KS1870 because of the pitch, the metric equivelent is N (some value) as the european way os to yuse N and P for negative and postive.

Even some FUji sheets refer to the KS and BH codes.cmacd

CS perfs (moved from Talk:35 mm film)

One thing must not be lost: The distance between the two hole rows with A(merican) C(inemaScope) or CS perf type is wider than with the other three types. ISO 491 --Filmtechniker 19:30, 19 May 2007 (UTC)

It's inherent in the film perfs dimensional descriptors. Girolamo Savonarola 20:32, 19 May 2007 (UTC)

Distance between holes is a function of both the height and the pitch of the perf. Neither this article nor Film perforations explicitly mention the pitch of a CS perf. Though since both claim CS sprockets run KS film, there's a weak implication that CS and KS share the same pitch, i.e. 1870. jhawkinson 20:40, 19 May 2007 (UTC)

I believe the comment was referring to the horizontal distance between two perfs, not the pitch. And given that CS perfs are the same height, there's no reason why the pitch wouldn't be the standard. In fact, Kodak's own catalog only offers an 1870 pitch for the CS pitch. Was this different in the past? Girolamo Savonarola 21:17, 19 May 2007 (UTC)

Right you are, that must be what was meant, though pitch is still missing. I suppose we should have a table for these numbers... Though it appears that the text of the article and the new diagram mix up the CS dimensions. Article claims CS are .073x.078, but the diagram claims .078x.073. I didn't mean to imply I knew about the pitch of CS perfs, other than clearly it must have the same pitch as KS1870 film if the same sprocket is to work on both (they need not have the same height or width since sprocket teeth are tapered). Of course, I guess there's the issue of shrinkage-during-processing, since all Kodak CS-perfed stock would have been on triacetate (I am not completely clear on how the specified dimensions interact with shrinkage. I seem to recall that 1870 shrunk to 1866 for acetate, at least with process ECP, and so short-pitch stock was a relatively recent phenomenon?) I assume you're aware that, btw, that Pylak has claimed on F-T that no one knows where the dies are for CS perfs, and you would have a hard time actually ordering any CS-perfed 35 stock today, at least from Kodak. jhawkinson 22:46, 19 May 2007 (UTC)

Good spot. I've fixed the diagram in question. Megapixie 22:27, 22 May 2007 (UTC)

Why don´t we simply give indication of standards ? There is ISO 491 to regulate this all. Filmtechniker 20:36, 22 May 2007 (UTC)

Filmtechniker - if you have access to ISO 491 - could you dig out the numbers - I'd be happy to include the inter perf distances on the diagram (I think I have a good way of doing it). I can see it as a 40 USD download on a dozen spec sites - but I'm too cheap to pay that much for a 66 kb PDF. Megapixie 01:20, 23 May 2007 (UTC)

sigh... apparently the diagram was correct and the text was wrong. I hauled out my copy of SMPTE 102 and checked. Presumably someone mis-transcribed it from Dom's book, but I don't have a copy to check that. So I guess the diagram was right. I'm sorry about that; I guess it'll teach me to speak up before actually doing research. I've fixed these 2 articles. (By the way, I don't think ISO 491 is controlling here over the SMPTE standards. At least, I never hear anyone cite ISO standards for this stuff, and it's not mentioned in Wikipedia. But perhaps it depends on where you live.) With respect to pitch, since pitch and interperf distance are related by the perf height, and pitch is the standard dimension that is quoted in the specs and orders and conversation, I think it would be much better for you to include pitch in the diagram, rather than some new quantity ("interperf spacing").

Anyhow, yes, CS-1870 is the spec with pitch, and as alluded to above, of course the pitch has to be the same as regular KS prints, otherwise CS sprockets couldn't run KS1870 film. So we should update these two articles to include the pitch. Someone feel free, or I'll get to it eventually. It does seem a bit funny, though, that there's no standard for CS1866 (or rather, that the standard is not simply titled "perforated CS" like SMPTE 139 is "perforated KS", and then discussing long/short within the standard) since presumably CS prints need to be made from CS negatives and intermediates. I guess maybe nobody was using CS perfs by the time they got around to writing the standards...Though Annex A.2 of S102 is written just like S139's, suggesting it might cover a CS1866... jhawkinson 07:20, 23 May 2007 (UTC)

(breaking ident)

It's easy enough to revert to my previous version of the image. Can we get agreement that it's that way round... (waiting for others to comment). Megapixie 12:44, 23 May 2007 (UTC)

It also occurs to me that it might make sense for you to draw the perfs along with the edge of the film, so you can show the distance from edge-of-film to edge-of-perf ("Dimension E"), rather than having the perfs horizontally centered. Of course, these are not numbers currently in either article...mumble mumble table mumble... jhawkinson 14:40, 23 May 2007 (UTC)

This is all getting a bit carried away. General information on perfs is great. Beyond that, let's move the conversation to Talk:Film perforations. Girolamo Savonarola 23:51, 23 May 2007 (UTC)

I don't have the heart to move the whole thread, but Be Bold. For the record, I corresponded with Dominic Case and he confirms that his book is in error on this point. jhawkinson 02:17, 24 May 2007 (UTC)

Everything up to this point was moved from Talk:35 mm film.

Pitch

I think there should be a clear distinction between "stocks intended for printing" (with short pitch size) and "print stocks" (long pitch), because it sounds very confusing.

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"See VKF Below"

In the "CS" section it reads, "See VKF, below." I can't find "VKF" anywhere else in the article. Maybe whoever wrote that will want to either remove the reference to "see VKF" or add something about "VKF." — Preceding unsigned comment added by Doug iowa (talk • contribs) 01:27, 3 March 2020 (UTC)

I removed this. It referenced a section that had been deleted referring to the VKF (very kind to film) sprocket design from Lavezzi. I'm guessing that was removed because it's a sprocket design and was listed as a perf shape. The VKF was designed for use with both KS and CS perfs (although it's too large to handle shrunken CS perfs). They also designed a Posi-Trol sprocket on which one of the teeth was wider than the other for better horizontal stability, designed only for use with KS perfs. It would make sense to add this information somewhere on the page, but the VKF and Posi-Trol should not be items on the perf shape list. — Preceding unsigned comment added by 2601:44:100:B910:3828:68E:8F4C:5FE0 (talk) 18:03, 23 May 2020 (UTC)