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How is motion picture film processed in the lab?


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#1 Alexis Mayer

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Posted 10 July 2006 - 12:13 PM

I'm curious to know the steps taken to develop motion picture film. I've developed my own still photography but are the general steps the same? Are the chemicals completely different? In what order are the steps done? What is the difference in the chemicals/processes used to develop reversal film as opposed to negative. What kind of machine is used in the lab to do the various stages of processing?

I'd love to know!
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#2 David Mullen ASC

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Posted 10 July 2006 - 12:18 PM

Color negative still film is processed in C-41 and motion picture color negative is processed in ECN-2.

One major difference is the remjet (the anti-halation backing) removal bath at the beginning of ECN-2, which is why you can't really run motion picture negative though a C-41 processor unless you want a lot of black carbon gunk in your developer and streaks all over your image. Remjet removal is also the reason why most people don't attempt to process motion picture film themselves.

Otherwise, conceptually it's the same in terms of developer, bleach step, fixer, wash, etc.

Reversal is a little more complicated.
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#3 John Pytlak RIP

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Posted 10 July 2006 - 12:19 PM

I'm curious to know the steps taken to develop motion picture film. I've developed my own still photography but are the general steps the same? Are the chemicals completely different? In what order are the steps done? What is the difference in the chemicals/processes used to develop reversal film as opposed to negative. What kind of machine is used in the lab to do the various stages of processing?

I'd love to know!


All you might want to know:

http://www.kodak.com.../....16.8&lc=en

http://www.kodak.com.../....15.6&lc=en

http://www.kodak.com.../....15.4&lc=en

In many respects, the ECN-2 process is similar to the still film process C-41. But it has rem-jet removal steps, and uses a different color developing agent (CD-3). The ECP-2D process uses CD-2, and has two fixing baths and soundtrack application (when silver soundtracks are required).

Machines are made by a variety of companies like Photomec, Technical Film Systems, Filmlab Engineering, Triese (RTI), Houston, Allen, Debrie, and others.
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#4 Dominic Case

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Posted 11 July 2006 - 03:18 AM

Apart from the sequence of chemicals, you might need to understand that motion picture film processing machines run as a continuous process. They consist of a series of tanks - typically a couple of meters deep, about a metre by 30cm across, each with a series of rollers at the top and bottom. Film is laced around the rollers in each tank, then into the next one and the next etc, so that when you start the machine running, the film spends a set amount of time in each tank. Each tank has a different chemical solution in it, so you get the film passing through the required sequence of chemicals.

We start off with the machine entirely laced up with dummy film or machine leader. The rolls of exposed negative are joined onto the end of the leader (which is in the total dark of course). As the machine runs, the neg is fed through the machine. When it's all passing through the machine, we join another roll of leader onto the end of the last roll of neg, so that we can run the neg completely out of the machine without stripping the rollers, and leave it ready laced for next time.

Time and temperature control are very critical. Temperature of the developer is controlled to +/- 0.1C, and the dev time is controlled to within a second or so by controlling the speed of the machine.

After the film has passed through all the chemicals and the final wash, it goes into a drying cabinet - another set of rollers - where heated, dried, filtered air is blown in. It takes several minutes for the film to dry, after which it simply rolls up onto a take-up roll, and all is done.

Simple really, I don't know why everyone doesn't do it at home :rolleyes:
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#5 John Pytlak RIP

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Posted 11 July 2006 - 07:37 AM

Here is a schematic of an ECP-2D processing machine:

Posted Image

Here is a compact processing machine made by Photomec:
Posted Image
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#6 Chris Keth

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Posted 11 July 2006 - 03:48 PM

Here is a schematic of an ECP-2D processing machine:

Posted Image



Funny, I always pictured the development and stop steps much darker than that. :D
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#7 Dominic Case

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Posted 11 July 2006 - 05:58 PM

Funny, I always pictured the development and stop steps much darker than that.


Chris, I guess if you pictured the dev & stop steps at all, you would be seeing too much :)

Anyway, John - great example of a picture worth a thousand words - or in this case at least 307. Good stuff as always.
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#8 Chris Keth

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Posted 11 July 2006 - 06:04 PM

Chris, I guess if you pictured the dev & stop steps at all, you would be seeing too much :)

Anyway, John - great example of a picture worth a thousand words - or in this case at least 307. Good stuff as always.



The funny thing is that, after doing so much B&W stuff in a darkroom for years I still see what I'm doing when I think about it, even though I've never seen it once. Wonder why that is... :blink:
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