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Old 18th October 2020, 03:37 PM
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GoodOldNorm GoodOldNorm is offline
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Default Olympus tech c41 processing

Thought this may be of interest to anyone doing C41

https://www.olympus-lifescience.com/...negprocerrors/
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Old 18th October 2020, 09:14 PM
John King John King is offline
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Default Not for me

I find it to be far too intense and technical for me. Too much reading and not enough substance. I gave up after the 2nd page.

Knowing all that will not make one iota of difference to my methods of working with C41
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Old 19th October 2020, 08:02 AM
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Quote:
Originally Posted by John King View Post
I find it to be far too intense and technical for me. Too much reading and not enough substance. I gave up after the 2nd page.

Knowing all that will not make one iota of difference to my methods of working with C41
I know that the article may not be for everyone, I posted it because I believe it may be of interest to someone just
starting to develop colour negative film. It may be useful for them to know what happens when you under/over develop colour film. These articles related to developing film tend to disappear without trace.
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Old 19th October 2020, 11:53 AM
Mike O'Pray Mike O'Pray is offline
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The intro was quite good but it did get technical and some of the "facts" such as the need to maintain the developer temperature to within 0.1 degree C might have be off putting to any newcomers wishing to try C41 development

0.1 may well be the "wisdom" but the inference a lot of newcomers might draw is that 0.11 might spell disaster which I don't believe it is.

It would have been interesting to see examples of colour crossover and a study of what temps bring this about

After all, some kits state that they can be used at other temps and indeed some users appear to have produced negatives that can be successfully RA4 printed by optical means from such kits

When this happens the response from the 37.8C brigade is that (a) they were just lucky on that occasion or (b) the conditions under which the negative was exposed was one in which colour crossover did not occur because of those conditions that existed at the time of exposure or remain hidden in the RA4 print

There has never seemed to be a scientific explanation Surely someone in Kodak or a photo chemist somewhere has done an experiment which demonstrates what if any is the increasing chance of colour crossover.

Yes, there does appear to be such a thing as colour crossover but nobody seems able or willing to give real information on this other than to say: do not exceed the 0.1 if you want to be sure of perfect negatives .

Then we wonder why, having given the impression of C41 being a "knife edge" process, that more newcomers just don't bother.

This situation for the few who may want to try optical enlarging for colour and RA4 printing is not helped by the fact that scanning it would appear can "repair " negatives allegedly or genuinely spoiled by deviating from the sacred 37.8C

However I accept that this aspect of C41 is not our territory but it is relevant to the the demise of home darkroom workers who wish to attempt colour work

Mike
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Old 19th October 2020, 03:18 PM
John King John King is offline
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Default Colour Crossover.

Mike, I have never seen a proper written explanation from a factory of how and when crossed curves happen. The mentor I had in the early days of my colour developing and printing was a person of few words, but each one meant something.

I quote. "If you over develop a colour negative at the correct temperature for longer than recommended, the characteristic curves designed by the manufacturer will not follow a more or less parallel upwards curve, one will speed ahead of one in a steeper incline or another will drop out of the curve."
]

He continued "The same 'can' - not definitely - will happen, if the developing is done at a higher or lower temperature even with amended times. The film/times and temperature are preset for optimum performance in the factory and anything outside these will affect the result. Over or under exposure will generally not affect except the balance only the in the density of shadows."

I have followed his instruction since around 1991 and the failures due to development I have had in that time can be counted on on hand with fingers left over.

Taking a picture with C41 in mixed lighting also gives the same indication but when checked the curves will have behaved as if the exposure development is perfectly normal. In all cases it will be almost impossible the correct these in a darkroom. It is possible in the intervening 30 or years that technology has advanced so far to enable the curves problem to be almost a thing of the past. Think here of Fuji Superia with the 4th layer which I understand helps with odd colours when using fluorescent lighting.

Last edited by John King; 19th October 2020 at 03:26 PM.
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