adjusting midtones

Hi all,

A newbie to the darkroom here, just finding my feet and trying to think some things through. I'm using Ilford RC multigrade papers mostly, with the occasional FB print.

While making prints I've had pretty good luck getting a normal contrast negative to print. I can dial in the brightest area of the print using exposure time, and then adjust the darkest area using contrast filters. I tend to think of the process in software terms, so . . .



. . . controlling the whites with exposure time is similar to adjusting the white slider on this histogram, and controlling the darks with contrast filtration is similar to adjusting the black slider on the left. Correct? More-or-less?

So my question is, how do I make adjustments to the equivalent of the middle slider in our histogram? In other words, adjusting the middle values of the whole image without dodging and burning specific areas.

I just read through "The quest for glorious midtones" post on APUG and that has me thinking about my exposures, but I think they're properly exposed. I think.

Thanks,

Jeff

Jeff, Have you investigated split-grade printing? I haven't used it but a couple of times. Googling the term should return numerous references (versions) for the method . . .

http://www.google.com/search?hl=en&q=split+grade+printing

When I print, I tend to use exposure to get the darks right, and contrast adjustment for the highlights. That's for normal prints where midtones and highlights are the most important parts of the photo. I sometimes do as you've described, but really, the exposure and the contrast have to work together to get mid and low just right.

As far as the slider analogy, the width of what paper can print is a subset of what the negative can hold for exposure information. Exposure changes move the print's portion of the histogram right or left. The film's portion of the histogram is the shape you see in the image above, minus the spike on the right which is probably a film carrier border or sprocket holes or perhaps it's part of the image and is blown out chrome reflections in the photo or something. Paper's range will be smaller as it's made to be less versatile or more exacting in exposure.

Contrast on a histogram is represented by a curve, not a place on levels. Film's contrast has a curve, and paper's contrast has a curve. PS level and curves are pretty much the same thing, except you can do more in the curves dialog box. In the darkroom, you move the print's portion of the histogram back and forth to take advantage of either the highlight curve or the shadow curve to favor contrast in certain tones. Split grade printing is intended to address this, but I haven't had a need yet, sort of HDR for the darkroom.

Some people use zone system processes to get negatives that are perfect to print without much trouble.

I don't. I mostly use sheet film or 120 and can shoot a roll of 120 completely of a certain scene or lighting condition. If it's high contrast scene and I want super nice highlights and nice shadows that will print well at normal contrast on paper, I make a note to develop that film in a pyro developer (I use pmk) instead of something standard like xtol/d76. A photo of a caucasian wearing black clothes on a sunny day is an example. I find I can then print for the midtones and the shadows and highlight will be tamer and respond with more "togetherness" to printing contrast adjustments. If it's a low contrast scene I'm shooting, I'll develop in xtol to get a negative of normal contrast.

I adjust the contrast of the midtones by choosing a higher or lower contrast filter for my main exposure. I adjust the time for that main exposure as well, to determine midtone density.

Then I make separate maximum contrast and minimum contrast exposures, as required, to adjust for shadow and highlight areas.

I dogge and burn as required.

Thanks for the responses; this is exactly what I was hoping for.

Dann - I have not looked into split grade printing so thanks for the link.

JP498 - I'm embarrassed that I described my own process incorrectly. I also use exposure to get the darks right, and contrast adjustment for the highlights. Mental hiccup there. Thanks for the suggestions.

Matt - thanks for the info. So much to learn.

Andrew Sanderson is a great teacher. Here's his Youtube video on split grading.

http://www.youtube.com/watch?v=5XgmJk2Fmpw

You need to use curves to adjust midtone contrast, not levels.

Levels will only push the midtowns lighter or darker.

With curves, you make the the center more steep compared to the ends. It is called an S curve.

Correct? More-or-less?

Click to expand...

Actually no. With the Ilford filter set on Ilford paper, changing contrast moves both black and white markers toward the center or outward. Adjusting the time moves the whole histogram to the right or left.