How would I test for this? (split grade printing, hype or real)

[Doremus Scudder]

The intriguing part of my musing is whether the change in the colour of the exposing light between exposures, and the differing responses of the emulsion components to that change, do make the order difference important.

Matt,
It's easy to test: Just make two split-grade prints, one starting with the low-contrast exposure first, the other with the high-contrast exposure first. Then compare.

The first exposure can simply be thought of as a pre-flash plus a subsequent exposure. So, with one print, you are essentially pre-flashing with low-contrast light, the other with high.

Best,

Doremus

 

[Augustus Caesar]

So, preflashing a sheet of paper will affect the outcome, but exposing first with warm light makes no difference?

Nope.

 

[john_s]

I was under the impression that pre-flashing gets the emulsion to the point where it approaches reacting to light, so any additional exposure starts forming an image immediately. It would seem that that would not work the same post-exposure. But what the hell do I know anyway.

That's what I thought too. So the argument goes from those who say it definitely makes no difference, that if you have an exposed film that you should have pre-exposed but didn't, you could give it some post-exposure before development. Could be handy occasionally.

 

[Pieter12]

That's what I thought too. So the argument goes from those who say it definitely makes no difference, that if you have an exposed film that you should have pre-exposed but didn't, you could give it some post-exposure before development. Could be handy occasionally.

Come to think of it, I remember DPs specifying “post flash” for motion picture film. So it is a valid technique to essentially bring up details in the shadows with negative film before processing.

 

[Augustus Caesar]

Come to think of it, I remember DPs specifying “post flash” for motion picture film. So it is a valid technique to essentially bring up details in the shadows with negative film before processing.

Yes, that was to keep the shadows from getting too dark in theatres. It doesn't really improve shadow detail, just keeps them from getting too dark, especially when doing day for night shots.

 

[Pieter12]

Yes, that was to keep the shadows from getting too dark in theatres. It doesn't really improve shadow detail, just keeps them from getting too dark, especially when doing day for night shots.

More than theaters. I was working on TV commercials.

 

[Augustus Caesar]

More than theaters. I was working on TV commercials.

Oh? I thought there were special low-contrast color print films for TV.

 

[Pieter12]

Oh? I thought there were special low-contrast color print films for TV.

Everything I was involved with was shot on color negative, the selects color-corrected and transferred in telecine. Later, it was all digital.

 

[Doremus Scudder]

What many here are missing about flashing, pre or post, is that it is an overall exposure, not filtered through the densities of the negative and, therefore, not proportional thereto.

So, to modify my initial response to Matt (which wasn't carefully enough thought through): an overall flashing will aid in adding density to highlight areas that would otherwise be underexposed due to negative density simply because it fogs the entire negative. This adds density everywhere, but, since the exposure is so low, makes little to no difference in the shadows and very little difference in the mid-tones; only the higher values are affected visibly.

Now, whether making this fogging exposure with low- of high-contrast light will make a difference in the subsequent contrast rendering of a print (ostensibly made at a different average contrast setting) really does remain to be seen. Whatever effects it might have, would be most noticeable in the highlight areas of the print. Anyone?

Best,

Doremus

 

[chuckroast]

What many here are missing about flashing, pre or post, is that it is an overall exposure, not filtered through the densities of the negative and, therefore, not proportional thereto.

So, to modify my initial response to Matt (which wasn't carefully enough thought through): an overall flashing will aid in adding density to highlight areas that would otherwise be underexposed due to negative density simply because it fogs the entire negative. This adds density everywhere, but, since the exposure is so low, makes little to no difference in the shadows and very little difference in the mid-tones; only the higher values are affected visibly.

Now, whether making this fogging exposure with low- of high-contrast light will make a difference in the subsequent contrast rendering of a print (ostensibly made at a different average contrast setting) really does remain to be seen. Whatever effects it might have, would be most noticeable in the highlight areas of the print. Anyone?

Best,

Doremus

Well, right, and this highlight density increase corresponds to a net reduction in overall contrast (when we consider contrast to be the range of light from lightest to darkest).

So, I'm not at all clear about the argument that preflashing increases sensitivity to subsequent exposure. I think the description here by @Doremus Scudder is much more to the point .

What am I missing?

 

[MattKing]

What am I missing?

There are two-three components to the emulsion.
Each component has a different sensitivity, as well as a different exposure threshold. And each component will respond differently when the colour of the exposing light changes.
Some exposures will be enough to put some of the components over the threshold, which will affect the results from subsequent different colour exposures. Whereas the same exposure from different colour light may be below the threshold for some of the components, so subsequent exposures to different coloured light will affect the image differently.

 

[Doremus Scudder]

...

Regarding flashing, exposure is cumulative, so it does increase “effective” speed, however at the expense of contrast in those lowest densities. That’s the tradeoff. It’s the same as flare.

Exactly.

So, is yellow flare different than magenta flare? That's the question.

 

[Carnie Bob]

Exactly.

So, is yellow flare different than magenta flare? That's the question.

I think not other than it would take more exposure for the magenta to hit the threshold you are looking for

 

[Jarin Blaschke]

This is all interesting to ponder in regards to pyro stain and contrast and what to do about shadows and highlights having different contrasts on VC paper.