Archived posting to the Leica Users Group, 2000/02/20
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Very thin emulsion films and vignetting has nothing to do with "simple geometry". Vignetting is recorded on film as a difference in density. That is what light fall off means. Less energy will be available in the corners. So less silverhalogenid is being activated. Now thin film emulsions have generally a steeper characteristic curve and in the case of Tri-X versus 100D the CI value is higher (more contrast for the 100D that is). This characteritistic makes the density difference more visible, but if you would measure both negatives with a densitometer you would note the vignetting equally well, when the films are developed to the same CI value. So it is not the thin film emulsion that does the trick. It is plain developing technique. Develop TriX to a high CI and you see nice vignetting too. Erwin