Cold light and Pyro

[Mouse]

Hi,
I have been reading about pyro last faew days and I think about giveing it a try. I have read that when useing pyro with variable contrast cold light head you can burn highlights with 0 contrast setting without affecting shadows and burn shadows with 5 without affecting highlights? Does it only work with cold light or does that work with dichro head also? Or is it true at all?
Thanks

[Drew Wiley]

Depends on the color of the cold light. I have an Aristo blue-green cold light which can
achieve results almost indistinguishable from what I get with a dichroic colorhead. With
the colorhead I use M or Y setting for split printing, whereas with the coldlight I project through either blue or green deep tricolor filters.

[Mouse]

That is just the thing that i want to know does the green/blue light has the same effect as the magenta/yellow light.

[Drew Wiley]

With variable-contrast paper the high contrast part of the emulsion is sensitized to blue light, while the low contrast emulsion is sensitized to green light. Magenta in a colorhead contains some blue light but blocks green, while yellow contains passes green but blocks blue. So it works just fine.

[ic-racer]

Hi,
I have been reading about pyro last faew days and I think about giveing it a try. I have read that when useing pyro with variable contrast cold light head you can burn highlights with 0 contrast setting without affecting shadows and burn shadows with 5 without affecting highlights? Does it only work with cold light or does that work with dichro head also? Or is it true at all?
Thanks

Yes, green/blue will work just like M/Y.

I wouldn't say "without affecting xxxx" as my experience is that there is some darkening of the opposite density, depending on how much you burn.

[Mouse]

So there is no advantage in useing cold instead of dichro light with pyro negatives?
I dont know why everywhere where i have read about pyro cold light is mentioned as advantage and not dichro.

[ic-racer]

So there is no advantage in useing cold instead of dichro light with pyro negatives?
I dont know why everywhere where i have read about pyro cold light is mentioned as advantage and not dichro.

Basically you are comparing additive (blue/green light sources) vs subtractive (Yellow/Magenta filters) printing on multigrade materials. The MG materials can't tell which system you are using.

My personal preference is to use subtractive dichroic filters, because they are precision graded, repeatable, don't fade and dichroic heads quite plentiful on the used market as commercial labs switch to digital.

[Drew Wiley]

To answer your question directly, no, there is no inherent advantage to using a cold
light. Sometimes I go back and forth between both a cold light enlarger and the dichroic additive, with a different neg loaded in each, but developed with the same VC
paper at the same time - did this just a few days ago. With a little practice, one can obtain identical results. Subtractive colorheads have a tiny bit of spillover of white light hypothetically affecting both emulsions, but it's apparently not enough to have any real visual effect. In other words, if I used my third category of enlargers, with true additive dichroic filtration (RGB), I wouldn't get different results on VC paper either. The brand of paper and its own idividual idiosyncrasies will have a much more
significant effect than your choice of light source (provided a cold light contains a
sufficient amount of both blue and green). An ordinary colorhead is a little more
convenient to use, because you can dial the settings so quickly.

[Mouse]

I thought since magenta and blue/ yelow and green are not the same wave lenght there would be some kind of visible diference.

[Drew Wiley]

No difference because the VC paper simply does not see the red component of either the magenta or yellow. In other words, the paper is sensitized to only to the blue light in the magenta filtration, and the green in the yellow. That is also why either a deep orange or red safelight is used for such papers.

[Brian Ellis]

"Without affecting" is a little extreme but the basic idea is accurate and it's pretty much a universal principle, not confined to cold light heads. Burning at low contrast, whether with a color head, a variable contrast b&w head, or a filter will affect the highlights much more than the shadows. And burning at a high contrast will affect the shadows much more than the highlights.

[Drew Wiley]

VC papers aren't perfect, but they are vastly better than they once were, and seem
just as good as the very best graded papers. But they rarely respond well to low
contrast filtration exclusively (Y or G); you need to punch in a little M or B. On the other hand, I have had several papers respond well to high contrast filtration only, provided the negative is appropriate for this. Often rather than true split printing, I will use some overall white light exposure first, then simply punch the highlights or shadows with strong filtration afterward. Of course this can be done selectively through burning in specific areas if needed. Many light sources aren't perfect either,
but for all practical purposes it is safe to make certain generalizations. With practice
it's quite easy. In fact, I don't even think about it much any more. I can switch back
and forth between different light sources almost subconsciously, although I generally
keep my two true additive colorheads immaculately clean for critical color printing,
where the distinction between additive and subtractive sources is more apparent
than in black-and-white work.