Re: Two tricolor prints
On Sep 26, 2007, at 6:25 AM, Marek Matusz wrote:
Katharine,Yes, but the overall low contrast is to some extent an inevitable result of setting the density of the negative to match the scale of the gum, which was part of my point. There's so much difference to be made up that it's very difficult to find a curve that will replace the contrast that you've lost, if that makes sense. If you have any slope through the midtones, then you sacrifice separation in the highlights or shadows or both. If you get separation in the highlights and shadows, then your midtones have to be flat. So far, I haven't found a curve that makes a better gum print than a diagonal line does (for my printer, light, negative media, etc) but I haven't given up yet.
I would think maybe I was missing something (which is entirely possible, since while I'm generally thought of as a fairly intelligent person and mastered statistics with no trouble, this stuff just makes no sense to me at all) except that a number of people have thoughtfully sent me calibration charts and curves to show me how I "should" be calibrating my curves for gum, and these have shown the same difficulty I'm struggling with. For one thing they have been made with underpigmented mixes, which I find interesting and somewhat inexplicable, but the main thing is that the post-curve step tablets seem to follow the same pattern: say in a 101-step chart, the steps from 1-10 or so show nice gradation, and the steps from 85 or 90 to 100 show good gradation, but all the steps from 15-85 are the same tone. And the curve reflects that exactly: a slope in the highlights and shadows, but horizontal through the midtones. Or, they have to lighten the highlights too much in order to leave room for a slope in the midtones. No matter what you do, something has to give. So I'm still struggling with that fundamental difficulty with making curves for gum.
But the problem here isn't so much with the curves as with the color; it's failing to block light where it should block it. This makes no sense to me because this color works for other kinds of prints; what should be paper white is paper white in all the other prints I've made using this color. These separations are the first place where I've seen this, gum printing where it shouldn't. It's really obvious when I print just the cyan layer, for example, using the two kinds of separation. The simple inversion separation keeps the blue off the poppies, leaving clean vibrant orange; the calibrated separation prints blue on the poppies, muddying the orange tone. There's no way to get rid of it but to brush it off, which isn't a kind of practice I want to get into. There's no logical reason for separations to be any different from other kinds of negative files, so I'm at a loss, but obviously if I'm going to use this calibration method for separations for tricolor gum, I'll need to go back to the drawing board and re-calibrate. I'm just really tired of fussing with the whole thing, was my point, and not yet convinced that it can yield good return on the investment of time, especially for tricolor separations.
Hmm, a couple of different things have got confused here, it looks like. I daresay I created that confusion by connecting this to a discussion about altering pigment to relieve darkness in a print, but altering pigments isn't what I'm suggesting here, and thanks for pointing out the confusion. The connection to the other thing wasn't pigment alteration, but a more general connection: the difficulty of relying on individually calibrated layers for tricolor, when the final result is more a function of the interaction between the layers than of the calibration of the layers. If you're going to calibrate for tricolor, what you really need is a sort of three-dimensional calibration, which makes my head ache to think of.so I would suggest correcting the curves not altering pigments.
No, I put the blame for this problem squarely on the negatives; there's nothing wrong with the pigments, as is evident from the other print. But it's interesting that you characterize this as a "dark" print; to my eye, I wouldn't call this dark at all. I called it "light and muddy" in my initial post about it, and I think that's an accurate evaluation. A quick check of the histogram bears me out; the median value of the left print is 118; the median value of the right print is 79; in other words, the left print is lighter by 15%.
My suggestion to reduce pigments for a dark print was intended for a very dark print, where the exposures for the individual layers are right but the tricolor is way too dark, as a result of overpigmentation of the layers. This print isn't remotely as dark as a print I would make that suggestion for.
The print with the "punch" is printed from the same kind of simple separations I've always used for tricolor gum; easy, quick, you're there, which was another part of my point; I didn't do anything special to achieve that effect; it's the same effect I get in every tricolor I've ever made, except for the ones where I deliberately muted the colors by adjusting the pigment. I'm hoping this example will help convince people who are intimidated by the whole curves thing not to be afraid to just go ahead and print. I'd say to them, you'll learn a whole lot more from printing tricolor gum than you ever will from printing calibration charts.
You're very welcome; I'm awfully glad to see the list reviving and some actual discussion going on. And I take your points; yes, probably more fiddling in that direction might yield a better print, but I'm at the point of diminishing returns. I'd rather be printing gum.Thanks for a great teaching example.