Contrast control.

I promised in an earlier post that I would tackle the subject of contrast control. My original idea was to explain the methods I use in the darkroom, but I think I need to mention why you might have contrast problems in the first place.

Are you having problems with excessive contrast in your negatives? are you finding it difficult to print them in the darkroom without a lot of messing around with filters? I could give you some pointers for methods to create good prints from them (and I will), but perhaps we should look at why those negatives are so contrasty in the first place.

The first thing I would like to say, is that you might find it strange that exposure is not the cause of your contrast problems. By that I mean that overexposure is not your problem, gross underexposure might give you very thin negs which are difficult to pull detail from, but I am referring to excessive contrast. You only get heavy negs if you overdevelop, and this is the real crux of the problem; Film development is where the contrast is caused. Over development causes increased contrast and grain.

Where are you getting your dilution, time and temperature information from? Some random person who wrote on Flickr? Something another student told you? Check your information with a reliable source, but still be cautious.

Following the developing instructions on the box or the bottle will get you a result, but your negatives could still be over developed if your thermometer is a little bit out, your measuring jugs are not very accurate and if you tend to ‘give a little bit more, just to be sure’. Another thing I’ve seen with students is, they take too long between pouring out the dev and getting the stop bath in, adding another 30 seconds to a minute to the development time. All of these things can make a difference and if you have a combination of them you might be quite a bit out from the ‘norm’. Remember; Over development causes increased contrast and grain.

So perhaps this is one area you might need to look at. If high contrast negatives are giving you problems, then I would suggest running a test film through and processing for 15% less time than normal (this is just a rough estimate, as I have no idea what your negs look like).

Normal and high contrast negatives (simulated).

Normal contrast

High contrast

The contrast is caused by allowing the dense parts of the negative to develop too long. This extra density prevents light getting through, either when printing, or scanning, leaving those areas to be totally white and without detail as a positive image. By careful control of temperature, volume and time, you can stop development at the correct point, giving you a negative with a long tonal scale that will print or scan properly.

Printing

If you have negatives in your files which are dense, how can you get a better print from them?

Split grade printing can be very useful for difficult negatives. There are many conflicting ideas about split grade printing, but I shall give you a simple and effective method. The secret to getting good results is in making the Grade 00 exposure first (I am assuming you know how to do the basics). Put a Grade 00 filter in, and do a test strip in the densest part of the image. Find out the exposure time for the subtle highlight detail you need, remembering that many papers dry slightly darker. Once this time has been established (and it could be a long exposure if the light has to get through your dense neg and the filter), expose a strip of paper for this indicated time Next, put a Grade 5 filter in and do a series of test exposures over the top. These exposures will not be as long as the Grade 00 because you are printing the thinner parts of the negative. Make this second test in a shadow area of the image.

When this two part test has been developed and fixed, look for the point where the black appears, and you will have your Grade 5 exposure. Give the full print these two exposures, working in the same sequence as before and develop the print.

The reason this method works better is that the Grade 5 exposure is not increased by the Grade 00 coming after it. (The effect is slight but it does happen).

To add to the technique above, you could pre-flash the paper to lower its contrast, though to be accurate, you would need to pre-flash the test strips and the final piece of paper to the same amount of light. If you want to get really ambitious, you can pre-flash through a mask to confine the pre-flash exposure to the highlight areas! This technique is a bit too much for this article, but I’ll be happy to explain and demonstrate if you would care to come for a workshop.

Let me know how you get on and write to me via the comments here or on Facebook and Twitter.

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6 thoughts on “Contrast control.

    1. andrewsandersonphoto Post author

      I am afraid you are mistaken Dehk. Try exposing a length of film and cut it into two sections. Develop one normally and double the time of development for the other. Then try printing or scanning from them and compare.
      Regards, Andrew.

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      Reply
  1. keith

    I usually start the timer before pouring in the developer and make sure it has been poured out in time for the stop-bath to go in. As you mentioned, temperature is critical as well. I am not a slave to dev-charts.

    Exposure is critical and I tend to err towards the generous side or even bracket with one at the recommended exposure and another at one stop over when in doubt.

    Perhaps you could upload a video on youtube to show how to take meter readings for b&w films for beginners.

    Thanks Andrew.

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    1. andrewsandersonphoto Post author

      Hi Keith, I have to disagree with you that exposure is critical. If you underexpose, you lose contrast and have to use a high contrast filter to print it. If you overexpose you should in theory get increased contrast. You state that exposure is critical, then go on to say that you overexpose. My point is that it is development which is important and you can easily control contrast with lessened development. Exposure is subjective depending on the look that the photographer visualises, but development must match the chosen exposure.

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