Contrast Control: Split Filter Printing

Polycontrast papers increase the ability to adjust contrast immensely. However, using the standard filter sets limit you to grades, nearly as constricting as using graded papers (let's not argue ‘constricting’ here— for the novice to intermediate printer, using graded papers IS constricting, not to say expensive…). This method, split-filter, or split-contrast, makes full use of the contrast controls, without limiting you to grade or half-grade steps. It also gets you to the correct contrast much faster than trying to predict what a particular grade will look like.

The method takes advantage of the particular sensitivity of the emulsion layers of polycontrast papers. Essentially, there are two layers of emulsion, one sensitive to green light, and one sensitive to blue. By using the compliments of those colors— yellow and magenta (respectively), you can manipulate these layers, and therefore the shadow and highlight areas, nearly independently.

The method uses two tests, one for the shadows (or dark areas) and one for the highlights. The final print combines the two exposures.

The Method

  1. The first test uses the #5 filter, and tests for the darks. You want to test an area of significant, or important shadows/darks. Keep in mind that this can be an aesthetic as well as a technical decision. After examining the image, tape down the test strip, and proceed with the test. Since the #5 filter is magenta, and rather dense, increase your increments from normal. I generally use 5 seconds.
  2. Process the strip completely.
  3. In good light, examine the strip. It's important here to remember that you are only testing for DARK values. There shouldn't BE any highlights. If there are, that exposure is too dark. Look for dark with detail, and note that exposure time.
  4. This is where most errors come in. Place a second test strip in the area of significant highlights (this may be in a completely different area of the print than you chose in step 1). USING THE #5 FILTER, expose the ENTIRE strip for the time you determined in step 3.
  5. Now change from the #5 filter to the #00. Run a test, right over that first exposure. Now we have the opposite as before regarding the increment. The #00 filter is (optically) thin, so it requires less exposure. I use 1 second increments at this stage.
  6. Again process the test completely.
  7. In good light, evaluate the test. Here we are looking at the highlights. (If you have a significant dark area, you can look at that, too). Look for white with detail, noting this exposure time.
  8. To make the final print, place the #5 filter in the enlarger, exposue your paper for the time determined in step 3. Then switch to the #00 filter, and expose for the time determined in step 7.

Notes:

—There may be a certain amount of 'fill-in' in the shadows when you print the #00 over the #5. To correct for this, reduce the #5 exposure time 10 - 20%.

—If you need to doing any burning/dodging, keep in mind which stage you should do it at. Highlights should be burned in with the #00 filter. Shadows dealt with when using the #5.