Specific ? Pyro (dye image) re EK's Tone Line process

[Clueless Winddancing]

For those of you who actually "know" and have done Tone Line along EK's process what do you predict would be the issues of getting the finest quality line outcome? Sure shooting 20X24 film would be a cure-all but I'd be using 4X5 B/W. While I'm acquainted with the process, what I don't have a line on is how would dye based images (Pyro negs) contact onto a CPO (or something like CPO) film?

I understand that film base thickness, and clear or diffuse spacer, and the angle of the contact frame's glass to the illumination affect the width so there are optimum to keep in mind. My goal is the most elegant line outcome for 4/5 shooting film. In the darkroom I can contact onto 5/7 for registration and projection.:confused:

[Nathan Potter]

I've did a lot of this some years ago but only using multiple lith film derivative images where each set picked off a slice of the overall density range of the original. I used typically 4 to 10 lith pairs to reconstruct a line drawing of the original. In 4X5 I used a registration system of course and exposed the final image thru the lith pairs with the bottom film image face down (contact) and the top face down with a clear 6 mil thick film between. So both derivatives were right reading. Plate glass held everything flat and a hair dryer was used as necessary to avoid newton rings. (Dust is a nightmare)

The exposing light source was a bare microscope light (essentially a point source) at a couple of feet distant from the copy. The angle from the normal of the copy was varied as you alluded to to change the width of the final line.

The key issue is the accuracy of the registration since any global misalignment is manifested as a varying final linewidth. So it's what you can tolerate visually. Simple projection geometry will tell you what you get. I usually used lith film as the final line image (Kodalith Ortho) but with lith film image creep is a variable.

The bottom line is that using a point source illumination with perfect registration line widths below 1 mil (25 micrometers) can be had. In a practical sense however look for 3 to 4 mil range at 4X5. Also realize that light scatter thru the three emulsions plus several air/film interfaces adds some degradation to the final image. Such scattering implies that a high contrast final emulsion is the way to proceed.

Nate Potter, Boston MA.