I don't understand. If the diffusion is between the light source and the negative, that will cause the light to be more diffuse and (Callier effect) will cause a drop in contrast and reduction in edge effects (apparent sharpness.) If the diffusion is between the negative and the lens and the focus point is the emulsion side of the negative, how can this not cause some softening of the image? I am a strong believer in glass neg carriers and I only get Newton rings if I have dust. I assume it is anti Newton glass - I will need to look at it closely based on this thread. I am confused about the use of Mylar though.
Frank