While experimenting with making Gum Prints over Van Dyke this past fall, I realized that RGB negatives contain more information than same image as a Gray Scale negative (subject of my last posts). I decided to explore this further and see how it would apply to my making full color gum prints.
Below is the curve I’ve been using when making full color prints using gray scale negatives. Complete workflow can be seen in my January 25, 2012 blog post http://tonygonzalezartist.tumblr.com/post/16491648522/gum-bichromate-workflow-2012
Below is a print made using the curve and gray scale negatives.
Next I made a new set of negatives using the same curve but with RGB mode negatives. Below are the results. Immediate observation revealed that although the curves translated identically on the graph, the prints however were different. The RGB negatives produced a much more contrasty print which resulted in loss of highlight detail (as seen in the elimination of clouds and sky in the RGB print).
What was needed was a new curve for RGB negatives that would replace the old curve with the gray scale negative. The graphs below shows the new curve (in red) compared to the old curve (in black).
The following prints show the comparison of the old curve with gray scale negatives (right), the old curve with RGB negatives (middle) and the new curve with RGB negatives (left).
The results of the new curve with the RGB negatives regained the highlight detail lost with the old curve using RGB negatives. The color, tones, density and contrast are also well balanced.
Next blog post, the new curve…