Contrast Grade vs. Exposure Time

[jcausey]

I'm taking my first B&W photo class in almost 20 years, and printing for the first time in that long as well.

We're printing using Ilford Multigrade IV RC paper, Ilford filters.

I'm trying to develop a feel for when to change contrast grades and when to adjust exposure time to get the look I want in a print. There have been times when I thought "I need more contrast" but simply exposing the print for longer gave it the look I needed.

My question is: are there any guidelines on when to adjust printing time and when to adjust contrast grades?

I tried asking my instructor, but she told me that she "had to re-learn B&W to teach this class and is not a good person to ask that kind of printing question."

 

[Donald Miller]

What I do is expose for the highlight values that I want and then determine if my low values are adequate. If too much of the low values are lumped together then I decrease contrast grade. If there is not an impression of adequate low values then the contrast grade is increased. This is for a typical print.

There are situations where one wants to render less then full contrast...in those cases print to what you want to portray.

 

[Kathy Harcom]

I tend to follow my instincts a little. In general I try and aim for clean and sparkling highlights and rich tones in the mid and shadow areas...an overall velvety feel. If the negative you are printing has a good range recorded it can be very easy to do, however if the negative has been under or overexposed then you can find yourself needing to explore a little until you get used to the effects of altering contrast and exposure time.

Increasing exposure can help, but there point at which your highlights will become muddy and the print will then lack 'life' as though a veil has been dropped over the print. At this point a change of contrast grade is necessary and can dramatically alter the feel of the print.

The best advice I could offer is whilst you are exploring your printing to stick to the one brand of paper like the Multigrade you are using and get to know it well. Make plenty of test strips looking at both the highlight details and the shadow areas, making sure you know see a maximum black. Keep development times constant, don't be tempted to pull a strip too early and confuse the results, if the test results at a particular contrast grade look lifeless, move up the contrast grade with the next test strip...if it looks too stark, hard and cold lacking richness...move down!

Also remember that as a print dries it does darken slightly (the dry down effect) and the extent to which it does this depends on the paper. You should therefore always determine exposure on a dry test strip. It is soft delicate highlights that can easily suffer from dry down as these might not be visible on a wet print. Always assess test strips/prints in good light.

All this said, personal style has a great influence on the way a print is made. It can be argued that a print showing a perfect range of tones in both highlight and shadow areas is what we should all aim for, but there are certain images and also certain personal styles that benefit from a different approach. I guess what I'm saying is that personal expression is ultimately very important...the print must satisfy you.

Well thats my rushed 2pence worth...hope it helps, and good luck!

Kathy

My question is: are there any guidelines on when to adjust printing time and when to adjust contrast grades?

 

[SuzanneR]

I also find it helpful sometimes to cut a sheet of paper up, and expose for different contrast grades, and compare them.

 

[BBarlow690]

Print to get the whites right, then judge contrast by the "feel" of the picture. There's only one question: "do I need more or less contrast to get the feeling of this picture that I had when I made it?" Answer that question, and then MAKE that print, with either more or less. You won't know until you actually SEE the other print. Even if the first print feels right, you'll learn a lot, and your seeing will improve.

 

[David Ruby]

The feel of the final result is what you're after, so don't forget that "Previsualized" image to put in in Les' words. It often isn't going to follow all the "typical" rules we follow.

I typicall start at Grade 2 which is basically neutral contrast for my test strips etc. I evaluate the highlights only. Then when I get that nailed down, I evaulate the shadows and adjust the contrast accordingly. Thus, change exposure for the hightlights and adjust contrast for the shadows.

You have to balance the rules with the end result. If you want a softer feel then you will typically use lower contrast. Higher contrast gives a harder feel.

 

[c6h6o3]

My question is: are there any guidelines on when to adjust printing time and when to adjust contrast grades?

Yes. You adjust them both with every work print until you get what you want.

Start with grade 2 and a standard time. I usually use 10 seconds. Then adjust, making sure that you always go too far (i.e. if you think that 20 seconds will be correct, give it 30 or 40). In this way you know you're homing in on the best possible print from that negative. Do this with contrast adjustments as well. You should have the optimal print nailed in 5 or 6 sheets. Then producing as many prints as you want is an automatic process. When you use this procedure you pick up a lot of valuable information about where you need to dodge and burn along the way, so the need for test strips is not only obviated, but becomes an actual hindrance.

 

[hansbeckert]

Build a print from the highlights down. Adjust the time until the highlights are right, then adjust the contrast until the shadows are right.