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'Aging' DI negative before processing


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#1 Eric Steelberg ASC

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Posted 13 January 2006 - 08:50 PM

Learned something new the other day. I'm just finishing the HD>35mm filmout for my Sundance feature at EFilm and was told somthing interesting I never knew. Each (lab) reel takes about 48 hours to 'shoot' on their ArriLasers. Before they send the negative to be processed, they need to let it sit for about 8 hours to 'age' it.

I asked "age it?"

He told me that since the first frame and last from on the roll are recorded about 48 hours apart, they need to let the film sit in order for the latter part of the roll catch up in age (chemically) to the first part of the roll. If it was processed immediately, there would be a substantial yet gradual color shift during the roll.

Found this very interesting and was wondering how this applies to other situations where time between shooting and processing might become an issue.

John? David?
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#2 David Mullen ASC

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Posted 13 January 2006 - 10:45 PM

Learned something new the other day. I'm just finishing the HD>35mm filmout for my Sundance feature at EFilm and was told somthing interesting I never knew. Each (lab) reel takes about 48 hours to 'shoot' on their ArriLasers.


48 hours to record out a 20 minute reel doesn't seem correct, but I could be wrong. But I can see waiting until all the reels are done so that they go into the same bath at the same lab.
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#3 Michael Most

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Posted 13 January 2006 - 11:47 PM

48 hours to record out a 20 minute reel doesn't seem correct, but I could be wrong.


It's not far off. If you're recording at 4K (which is fairly common, even when the source files are 2K), the Arri Laser takes about 4 seconds per frame. Multiply this out and for 2000 feet, it's about 36 hours.
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#4 Eric Steelberg ASC

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Posted 14 January 2006 - 02:29 PM

48 hours to record out a 20 minute reel doesn't seem correct, but I could be wrong. But I can see waiting until all the reels are done so that they go into the same bath at the same lab.

I was surprised too especially since another place said it's about 24 hours per reel. Now that I think about it though, maybe I misunderstood and it was 48 hours for all 5 reels divided between x number of ArriLasers. He also said there is about 20% added time per frame for the anamorphic squeeze.

He was very clear about the aging thing. I also asked about them all being bathed together and he said they're running control strips with Deluxe about 10 times a day and as long as the LADs are hit, they can process the reels as they come off...after aging.

Would love to hear what John Pytlak says about it all.
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#5 Dirk DeJonghe

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Posted 15 January 2006 - 06:48 AM

In my experience, the latent image of color positive stocks ages worst, with up to 3 B&H density points loss of speed over 24 hours.

When I record to positive stocks on my Lasergraphics, a compensation has to be added unless it is a very short film. 20 minute reels take about 20 hours to record so I plan it to finish about 12 hours before processing.

Camera stocks and intermediat stocks are much less of a problem, I could not detect a practical difference between immediate processing and 24 hours later. There may be a difference but it gets lost in the noise.
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#6 Dominic Case

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Posted 15 January 2006 - 06:43 PM

There certainly is an effect known as latent image fade that affects all stocks.

Labs that expose their own senso control strips usually make a batch, age them for up to 24 hours, then freeze them, so that the first one used will be the same as one used several days later. Otherwise you can easily see a change - it rarely amounts to more than a trim or so, and this might get lost in a lot of work, but is, of course, critical for the control strips themselves.

Quite a few years ago I had to shoot complete rolls of lab "chinagirl" for printer control use - and obviously this would have to be consistent to less than a printer point or trim. As I shot a couple of thousand feet at a time, shooting live didn't work out - the model had to sit still for the entire shoot, and tended to get hot or cold, to blush, or to move. When I shot on a rostrum camera from artwork, the camera took several hours to get through a roll, with the resultant latent image shift between start and finish. Aging ensured that the whole roll was uniform, but every test had to be aged the same amount. A nightmare.

But it only seems to present as a significant problem if you need a precise result that you intend to measure rather than assess visually, and if you would normally process immediately after the end of the exposure run.


Efilm have 13 Arri Lasers, so they obviously know what they are doing with them.
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#7 John Pytlak RIP

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Posted 16 January 2006 - 10:47 AM

Yes, letting the exposed roll "age" for a bit will reduce the small but measurable change from head to tail that may occur due to any latent image keeping. Another issue is sometimes the temperature of the exposed roll on the equipment. Keeping the film cool helps reduce any latent image keeping changes. The changes are slight, but they are measurable, and can be minimized with "aging" stabilization, and cooler operating temperatures.
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#8 Brad Grimmett

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Posted 17 January 2006 - 05:53 PM

Eric, what film do you have at Sundance? I'll be in Park City until Sunday and will try to check it out if it's playing while I'm there.
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#9 Clive Tobin

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Posted 22 January 2006 - 02:55 PM

.... Before they send the negative to be processed, they need to let it sit for about 8 hours to 'age' it.


We had a similar problem, only worse, on an optical printing job I was doing some decades ago at Alpha Cine.

I was converting some Techniscope 2-perf footage to 4-perf 1.85:1 on a Reserch Products optical printer, to CRI 5249. We didn't have a 2-perf projector movement, so we made up a Rube Goldberg setup with a capping shutter on the camera, running in the skip printing mode. We did one pass exposing every odd frame of the CRI, then backed everything up, moved the negative 2 perfs, and exposed every even frame of the CRI.

To our great displeasure, after days of work and much expense, we discovered that the resulting film had a severe 12 FPS flicker owing to the two passes being exposed hours or days apart. We had to age the subsequent CRIs for a long time (I forget now how long) to wash out the differential aging.
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