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skip bleach and cross processing


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#1 Roberflowers

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Posted 12 April 2006 - 04:44 PM

I understand that pushing a stock seems to make it "faster", although my professor has reiterated it to me and my class that it does NOT make it "faster", but really makes it more contrasty...The D log E curve is steeper. Although I think it may seem brighter when you do push the stock...That being said, is the same true for photochemical processes such as, skip bleach processing and cross processing. Does it feel "faster"? Is this a psychological thing?

I'm thinking about incorporating one of these processes for a short I''m to photograph in August, I'm just curious as to what people think, before I go out do some tests myself.
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#2 Dominic Case

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Posted 12 April 2006 - 05:42 PM

Your professor is correct.

All of these processes act to increase the contrast and the density on the negative.

That means in many cases (depending on what you are using the process for, of course) you can reduce the exposure.

Which means you can rate the stock - say- a stop higher.

But that doesn't actually increase its speed in terms of its ability to see lower light levels.
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#3 Michael Nash

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Posted 12 April 2006 - 05:43 PM

I think you may be partly misunderstanding your professor.

It's not just an illusion of contrast. Push-processing a negative increases the density, so underexposed midtones can be brought back up to a "normal" density. However contrast, color saturation, and graininess are also increased. And of course you're not extending the range of shadow detail the negative can capture, just "boosting" the density of what's there.

Regarding the other chemical processes, each one is unique:
http://www.theasc.co...ujour/index.htm

Skipping the bleach bath on a negative leaves the silver in, adding to the density (an overexposed positive), among other things.

Silver retention on a print adds to the print density, resulting in a darker shadows but less affected highlights (i.e. more contrast, with mild darkening of the mids) -- again, among other things.

Cross processing tends to increase the contrast dramatically, so midtone exposure might be close to normal but shadows and highlights can get away from you very quickly -- again, among other things.

But there's no getting around testing, as the results are not 100% predicatble 100% of the time.
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