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Controlling Print contrast


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#1 Marc Roessler

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Posted 13 November 2008 - 05:39 PM

Hi guys..

To the best of my knowledge, for b/w development there exist two ways to control contrast in the final printing stage (given an already processed negative):
- processing time
- processing bath temperature
Is there any other way such as using filters, as is done with photo proecssing to control gradation?

What are the advantages/disadvantages of modifying time when compared to modifying temperature, both from a technical (concerning the image characteristics) and practical (time needed to skip rollers when threading etc) view point? For example, can it happen that the development times get too short when trying to lower contrast, thus resulting in uneven development or similar problems?

Which of those techniques can be used for color? Is color print stock more susceptible to color shifts than color negative stock when push/pull processing?

Thanks & Greetings,
Marc
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#2 Marc Roessler

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Posted 13 November 2008 - 05:54 PM

Oh and by the way.. what will happen to the analog sound track when doing this?
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#3 Brian Pritchard

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Posted 14 November 2008 - 04:09 AM

Hi guys..

To the best of my knowledge, for b/w development there exist two ways to control contrast in the final printing stage (given an already processed negative):
- processing time
- processing bath temperature
Is there any other way such as using filters, as is done with photo proecssing to control gradation?

What are the advantages/disadvantages of modifying time when compared to modifying temperature, both from a technical (concerning the image characteristics) and practical (time needed to skip rollers when threading etc) view point? For example, can it happen that the development times get too short when trying to lower contrast, thus resulting in uneven development or similar problems?

Which of those techniques can be used for color? Is color print stock more susceptible to color shifts than color negative stock when push/pull processing?

Thanks & Greetings,
Marc

Normally you would use whatever combination of time and temperature suit your processing machine so that if the machine was set up to give maxmium throughput you would need to reduce temperature. Running very slowly or very fast can affect the evenness of development. Also, of course running faster to reduce the contrast will mean that all the other stages will get less time so you might have a problem with correct fixing and washing.

It is not normal to alter development times in colour print processes as you will get unwanted effects such as differantial shifts in the contrasts of the three layers giving rise to cross-overs; red highlights and cyan shadows for example.

There are other ways to reduce contrast in a print such as pre-flashing the stock (this can also be used for colour print) and a stills technique called unsharp mask. You can read about this technique in any good stills photography manual. Another technique is to make a lower contrast dupe negative, and dupe positive if required.

You can't use the filter system that is used in Multicontrast paper because it is coated with two emulsions with different contrasts that have different colour sensitivities. Changing the colour of the light source changes the contrast.


If you alter the processing time or temperature the change will also affect the contrast and density of the sound track. The change in density will have to be compensated for during exposure. The change in contrast should not be a serious problem as far as sound quality is concerned as long as the density is right.

Brian
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#4 Simon Wyss

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Posted 14 November 2008 - 05:59 AM

Fine tuning of print contrast is the real art of copying because you want to develop out maximum density in the deep shadows and have blank spaces in highlights at the same time with a pleasing grey scale image. There are different stocks on the market for printing purposes. Filmotec have - as a novum - a positive material with an anti-halo undercoat, the Orwo PF 2 plus. It's intended for use with dense (archival) negatives.

I have nine years of practical experience in hand processing. When you give in with the belief that motion-picture films must be treated in machines you can find out about the advantages of manual treatment. One of them is flexibility. It is possible to change developing time at once, also to change baths, temperature (within minutes) and more. It is a fact that the results are most even. I refer to treatment in spirals.

Let me cite a much more experienced laboratory technician: "There are film-makers who demand that film processes must be more constant and repeatable than they are, that the laboratories obtain exactly what he or she wants however well or badly shot the film was, and that the lab go on making print after print until it is right. These unfortunates do not understand the real truth - that photographic chemistry is closer to cookery than science - that there is an inherent variability in chemical processes which we do not have the funds, equipment or, in some cases, the understanding to control." *

He appears to have a bitter undertone, must I say. What has almost gone lost is the freedom of practice known in the silent era. There was close hand-in-hand collaboration between cameramen and lab people. Most camera magazines did not hold more than 200 feet of film, lengths that can be handled with racks or reels (spirals). Only the Pathé industriel and the Debrie Parvo took 400-ft. cassettes for some time. Positives were broken down for individual processing now and then. This was entirely swept away by the mechanical treatment of the photographic sound films.

* Paul Read: A Short History of Cinema Film Post-Production. In: Weltwunder der Kinematographie, tome Eight; Polzer, Potsdam, 2006. ISBN 3-934535-26-7
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#5 Brian Pritchard

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Posted 14 November 2008 - 06:54 AM

You have to bear in mind that not all laboratories are in a position to alter parameters for processing and printing. Laboratories specialising in film preservation such as the laboratory at the bfi/National archive, will process almost every duplicate and print differently to get the exact match when copying sections from different generation masters.

Major laboratories, who in the heyday of film production might be printing and processing 5 million feet a day, had to maintain the processing and printing to exact standards so that prints made today will be the same as prints made last year and that duplicates were processed so that you obtained the best possible result. They did not have the time to alter parameters to suit individual cinematographer unless he had a lot of clout such as Stanley Kubrick and was having thousands of prints. You have to go to a smaller lab to try experiments and be prepared to pay the price.

Processing camera negatives was different. Every cameraman did gamma tests before commencing the shoot so that the lab would know what speed to process his film. Every batch was different and required different development times and Kodak would select batches to match a previous batch if the particular emulsion ran out during the shoot, One of my first jobs in the industry.

Brian
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#6 Serge Teulon

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Posted 14 November 2008 - 09:26 AM

As previously mentioned I don't think that changing the speed or temperature of your processing bath to achieve those effects is a sound option.
Most effects such as lowering contrast, in my experience and opinion, should always be done in camera.
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#7 Serge Teulon

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Posted 14 November 2008 - 09:52 AM

As previously mentioned I don't think that changing the speed or temperature of your bath to achieve those effects is a sound option.
Most effects such as lowering contrast, in my experience and opinion, should always be done in camera.
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#8 Brian Pritchard

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Posted 14 November 2008 - 10:11 AM

As previously mentioned I don't think that changing the speed or temperature of your bath to achieve those effects is a sound option.
Most effects such as lowering contrast, in my experience and opinion, should always be done in camera.


I don't know how you alter the contrast of a negative in camera unless you change the lighting ratio but that is not always possible.

What we were discussing was making a print from a negative already made, which has high contrast. In that case you have to try to make a low contrast print by one of the methods mentioned.

Brian
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#9 Serge Teulon

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Posted 14 November 2008 - 01:13 PM

I don't know how you alter the contrast of a negative in camera unless you change the lighting ratio but that is not always possible.

What we were discussing was making a print from a negative already made, which has high contrast. In that case you have to try to make a low contrast print by one of the methods mentioned.

Brian



One of the answers to your first point you've already answered. The other options are by either flashing or by rating your film stock slower than it actually is. i.e rating 500 asa at 320 asa. The choice of which technique to use completely depends which way you want to go.

In regards to your second point, I must have misread as I didn't pick that up. Apologies.
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#10 Brian Pritchard

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Posted 14 November 2008 - 02:49 PM

One of the answers to your first point you've already answered. The other options are by either flashing or by rating your film stock slower than it actually is. i.e rating 500 asa at 320 asa. The choice of which technique to use completely depends which way you want to go.

In regards to your second point, I must have misread as I didn't pick that up. Apologies.


Changing the exposure won't alter the contrast; over exposing will push the highlights up onto the shoulder of the curve, giving loss of shadow detail in the print. Underexposing will lose highlight detail in the print, the sections on the straight line will still have the same contrast.

I would never recommend flashing a negative stock before exposure, there is too much danger of static, scratching, uneven exposure etc. If you make an error your film could well turn out to be useless. Such techniques should, normally, be confined to laboratory work, in my opinion.

Brian
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#11 Serge Teulon

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Posted 15 November 2008 - 07:27 AM

Changing the exposure won't alter the contrast; over exposing will push the highlights up onto the shoulder of the curve, giving loss of shadow detail in the print. Underexposing will lose highlight detail in the print, the sections on the straight line will still have the same contrast.

I would never recommend flashing a negative stock before exposure, there is too much danger of static, scratching, uneven exposure etc. If you make an error your film could well turn out to be useless. Such techniques should, normally, be confined to laboratory work, in my opinion.

Brian



Brian, anything can happen in the lab as well!! That is one of the main reasons why most dp's and directors will always do more than one take per slate.
As a dp I'm even more confident in saying, after testing, that the percentage of error is higher in something going wrong in the lab than it is in camera.
There is also the whole control thing too.
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#12 Brian Pritchard

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Posted 16 November 2008 - 04:27 AM

Brian, anything can happen in the lab as well!! That is one of the main reasons why most dp's and directors will always do more than one take per slate.
As a dp I'm even more confident in saying, after testing, that the percentage of error is higher in something going wrong in the lab than it is in camera.
There is also the whole control thing too.


Serge

I wasn't pointing a finger, what I was trying to say was that if you carry out flashing before exposure on your camera film and something goes wrong you have to re-take, if that is possible. If you do the work in the lab then you still have your camera original safe. I am a great believer in the principle that if you start out with a correctly exposed, normal camera original you can then do what you please in the lab or when making a digital intermediate.

I am not against experimentation provided it doesn't matter if it turns out wrong. If someone wants to run their negative through the camera wet, then fine, but don't photograph an unique event in case it doesn't work out.

Brian
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#13 Serge Teulon

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Posted 16 November 2008 - 03:40 PM

Hey Brian,

I didn't mean to come across as if I thought that you were pointing a finger. I feel sometimes that certain punctuations don't actually carry ones' true sentiments.

I understand your point.
But at the same time I must say, that I take pride in techniques that I have learnt and I truly believe that techniques are what separates a cinematographer from the rest.
To bring my individual skill and talent to the table is the reason why someone will hire me or any other cinematographer.

I don't think that a cinematographer should rely on just one process to achieve the effect, heck, we should use everything at our disposal, if it adds to our work.
But you have to ask yourself whether effects like what you have seen if recentish films such as Saving Private Ryan, Diving Bell and the Butterfly, Man on Fire, Assassination of Jesse James etc..should've been achieved outside of camera. I truly think not!

It is the work of a cinematographer to do, not a lab technician.
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