DETERMINATION OF OPTIMUM PAPER EXPOSURE


There is no universal paper exposure time.  It varies according to the type of enlarger you use (condenser, diffuser, cold light, point light, etc.), the amount of flare that your enlarger lens produces, the amount of flare that your enlarger light-system produces, the print magnification, the type of paper you are using, the density of the negative, and many other factors.  If you use the exposure times that someone else recommends, you are probably not getting the best results that you can since their situation is not exactly the same as yours. Little differences in these factors can lead to big differences in your results.

1. Select any combination of film and paper to test. The tests must be re-run if you change film, paper, developer, enlarger, enlarger lens, toner, special techniques, etc.  There are a lot of things that can affect the outcome of these tests, so it's best to be as rigorously consistent as possible.  

2. Find the shortest exposure time that produces maximum black on the paper.  Exposure times shorter than this would mean that your pictures are not as rich in the dark areas as they could be.  Exposure times longer than this would mean that you are losing brightness in the highlight areas of your prints or using too low a film speed -- or both.  This test needs to be rerun for each enlarger lens that you have.

Now that you know how to correctly expose the paper, you're ready to move on to DETERMINATION OF OPTIMUM FILM DENSITY.

3. In step #2, you determined the best exposure for this type of film/paper/developing combination.  But there are times when you will need to change the exposure of the paper.  First, is artistic licensce.  Perhaps you prefer the scene to be slightly darker than it really was.  In this instance, you'll need to change the exposure according to your preferences.  Secondly, if the negative was incorrectly exposed or developed, a change in the exposure of the paper can help.  It will not save the day completely, and how much to over- or under-expose the paper depends on how badly over- or under-exposed/developed the film was.  The only other time that you will need to change the exposure of the paper is if the magnification of the print is changed.  Most darkroom workers determine changes in exposure with the use of test strips -- a waste of time, paper and chemicals. With the formula below, you can skip this step.  


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