A set of filters with which to control printing contrast is about as basic a tool in the black-and-white darkroom as a pair of print tongs or a thermometer. And that makes them very easy to take for granted. Pull out a number 3 filter and it’s obviously a 3—not a 21⁄2 or 31⁄2—definitely a 3. Or is it? The answer is, naturally, “it depends.”
Such filters have been around since the days of Du Pont’s Varigam system and are available to this day under perhaps a dozen brand names. We selected two of the better known, Ilford Multi- grade and Kodak Polymax filters. Several boxes of each were evaluated by printing step tablets through them and noting the actual paper-contrast grade obtained with each filter. Of course, it would be futile to conduct such a test with a paper incapable of achieving a full range of contrasts in the first place, and, as explained in our March/April 2005 PT report on variable-contrast papers, that is indeed the case for many products. The data we report here are for a certifiably full-range paper, the glossy version of Ilford Multigrade IV RC Deluxe paper. Virtually identical results were obtained with other well- designed papers, and for assorted surfaces.