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65mm stock indexing


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#1 Phil Rhodes

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Posted 11 February 2010 - 01:04 PM

OK, so indexing on 35mm stock looks something like this:

1234+12

where 1234 represents feet, and 12 represents frames. This works for 35 (exactly 16 frames per foot) or 16 (40 frames per foot) or even 8mm (80 frames per foot).

But what d'you do about 65mm five perf (12.8 frames per foot) or god forbid 15 perf (4.267 frames per foot)?

Rounding things to the nearest frame boundary gives a sequence that looks like this:

74+00
74+01
74+02
74+03
74+04
75+01
75+02
75+03
75+04
76+01
76+02
76+03
76+04

This might be a perfectly valid way of indexing frames on 65mm stock, but it's ugly and counterintuitive that we never see 75+00 or 76+00.

What's the solution here? How is this supposed to work?

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#2 David Mullen ASC

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Posted 11 February 2010 - 01:45 PM

Didn't Kodak change the keycode placement on 65mm a couple of years ago for this reason?
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#3 K Borowski

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Posted 11 February 2010 - 01:46 PM

It could be even uglier, if you use meters :-p


In seriousness, 4-perfs are 3/4 inch (or close enough), so shouldn't each frame be 3/16"? Or, for those of you that are Imperially/fractionally challenged, that is 0.1875"/0.47625mm.

I know that this isn't exact, and is even more complicated now that pitches have changed and with acetate vs. estar (8 perf.'s on acetate is NOT 8 perf.'s on ESTAR), but can't you just bypass all the measuring BS and base measurements on perf.'s flat-out?


Of course, NLE editng, keycode, and inked in edge marks aren't my department, so I apologize if I am missing your point completely.
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#4 K Borowski

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Posted 11 February 2010 - 02:22 PM

EDIT: 5/16" for 5-perf.
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#5 Dominic Case

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Posted 11 February 2010 - 08:19 PM

David could be right.

But this seems to be the same problem that comes up with 3-perf 35mm, with 21 1/3 frames per foot.

I seem to recall that this flummoxed most of the neg matching software around in the 90s. The solution involved defining a reference frame at the start of a shot by the position of the Keycode reference dot relative to the top perf of the frame. You don't need to see the actual way the computer referrs to a given frame, so ugly counter-intuitive number sequences aren't a problem. (At least not any more than they are in 3/2 pull down, dropframe timecode, or days of the month for that matter.)

In the case of 65mm, the defining issue is to know which footage numbers in a sequence actually have 00 frames. The next two won't, but where to start??
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#6 Phil Rhodes

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Posted 11 February 2010 - 09:39 PM

Evertz have cooked up some sort of solution, which they claim other people are using, for 3-perf 35:

http://www.evertz.co...urces/3perf.pdf

...but it seems barely less involved than just rounding to the nearest perf.

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