From Richard Newman Split contrast printing is going to give different results than the intermediate filter, but to work with it, some calibration will be needed. If you have access to the different gamma curves for your filters, and the right software, you can get a reasonably good estimate by summing gamma values under the curve for each filter, film density and exposure. More realistically, I suggest doing a set of test prints to give you starting points for determining how to expose. There are essentially three variables involved, assuming that the paper and processing dont change. They are the filter value, the density of the negative at the points of interest, and the relative amount of exposure given under each filter. Assume that you wish to use a number 1 and number 5 filter, and that you will give equal exposure time under each, to the print. Photograph a ten to twenty step gray scale such as Kodak, and develop it so that the steps are correctly represented on the negative. I suggest bracketing exposures in half stops to be sure of getting a good negative. Then do a whole series of prints. Do one each with each filter in your set, or at several points if you have a variable head. Then select two points on the gray scale, one near each end, and use them as your references for shadow and highlight. Expose under whatever combinations of two filters you want to test, and process them all together. Before exposing, mark each print on the BACK with the conditions of exposure. If you want to vary the relative exposures under the two filters, fine, it just takes more prints. Because of the number of prints, I suggest using 4X5 prints. They will give you enough area on each step of the gray scale to look at. When the prints are dry, compare them. They will show you how each combination affects different densities. Also, when setting up to do two filter exposure, the reference set will help you get it right the first (or second?) time. If you change your paper, light source, filters or processing, it may change the results, and you may need to make additional prints to check if there is a shift. Will the difference using two be sufficient to make the effort? Only you can decide.

-- Richard Newman (rnewman@snip.net), April 10, 1998

Answers

split printing

Split printing is a method that I often use ,but i should say , not as common practice. The reason is that the difference between split and "straight" printing is subtle not dramatic. In most cases straight filtering will achieve fine print results. That beihg said, let me make these suggestions and clear up what I believe to be a bit of mis-information given on this subject. First- Proper exposure times for both filters can be acheived by simply running one exposure over the other and creating a cross hatched test strip. Run the low contrast exposure at the smallest repeatable time from say left to right and then follow on top of that with a second exposure with the high contrast exposure from top to bottom, again using the smallest repeatable exposure. Second- If using two seperate test exposures the proper exposures would be the time just before texture white for the low contrast and just before black for the high exposure. This will consider the additional exposure given by each that will add density to these areas. Third- The Zone VI VC head is not the only unit on the market that will give proper results. In fact IMHO is not the best head of this type. In the same note a dichroic head can be used to some effect in split printing, but can require the addition of VC filters to intesify the color shift.

-- jim megargee (mvjim@interport.net), April 14, 1998.