Determining Final Print Contrast?

[tgtaylor]

Suppose that an initial exposure on VC paper was X seconds with a #00 filter followed by Y seconds with a #5 filter. What is the resultant contrast of the print

Thomas

[Daniel Stone]

I'm assuming that this is a "straight" print, no burning or dodging at all?
A few years ago, when enlarging primarily MF negatives, I did the same thing. Base(1st) exposure at say G2.5, then burning in the sky w/ a G4 or so. This was on MGIV.
I just used my eyes to gauge what I liked, and kept good notes according to the #s on prints(in pencil on back before exposure/processing) in order to keep things honest.
But in terms of "gauging" a contrast between the two, I'm not sure how I'd go about doing that. But I'm no whiz-kid when it comes to this stuff, I just use my eyes to determine what works and what doesn't for a particular negative/print

-Dan

[Vaughn]

Depends on the contrast of the negative.

[Michael Graves]

As Vaughn says, negative contrast has a significant impact. But so does the value of X and Y. Contrast is changed by changing the two times. More time with #5 gives more contrast and vice versa. Additionally, I've found that different papers respond differently to split printing. So I don't think there is a cut and paste answer to your question.

[RickV]

http://www.waybeyondmonochrome.com/W...rintingEd2.pdf

This explains it very concisely.

[Dave Grenet]

But it doesn't quite answer the question in the OP. I don't have an answer, but it is something I've wondered and will, at some point, find out for myself.

If you have a step tablet you can do the experiment yourself. Simply find what times are needed to match the other contrast grades, and fit the data to the equation. Obviously matching with a densitometer would be best but visually would do for me, or I might find a way to use my scanner...

[Cletus]

Isn't the OP just talking about split-grade printing? AFAIK, the whole point of split grade printing is that you can basically get a stepless print contrast control, as opposed to using straight filters for VC printing, where 1/2 grade is the best you can get.

I've found split-grade techniques useful with difficult, very high or low contrast negatives that were hard to judge an appropriate filter grade. I'm not sure whether this answers the OP's question or not. I suppose if "x" (00) time was 50% of the total exposure, making "y", or Gr 5, the other 50% you'd presumably wind up with approximately grade 2.5 in the final print.

Here's a reasonably good article taken from Les McLean's website on the subject....

http://www.lesmcleanphotography.com/...ull&article=21

[Peter Lewin]

I'm not sure that the original OP's question has an answer, at least not a straight-forward mathematical equation, because it will not be linear. Half the time at grade 0 and half the time at grade 5 will in all likelihood not yield grade 2.5, because paper speed is not constant, if you look at manufacturer's ISO ratings, they vary by grade. So equal time for different grades will not give you equal exposures at those grades. Both the contrast in the negative, and the grade vs. speed graph of the specific paper will factor into the answer. That is precisely why split grade printing is done "by eye," first finding the "soft exposure" that gives you the highlights you want, and then finding the "hard exposure" that yields the blacks you want.

[C_Remington]

I don't even understand the question. What are you looking for? Something like Grad 3 at 2 minutes???

[Andrew O'Neill]

Can't answer your question. Depends on certain factors, the main one being negative contrast as mentioned. Are you looking for more control when split printing? If so, take a step wedge of known DR and making several exposures varying the exposure for the yellow and 00 filters. That'll give you a better idea.