Re: Strange Thing with Step Wedge

Wayde Allen (allen@boulder.nist.gov)
Fri, 25 Jul 1997 09:03:08 -0600 (MDT)

On Fri, 25 Jul 1997 FotoDave@aol.com wrote:

> Since I made more than 1 enlargement from the step wedge, I re-read the
> densities of all of them and found that the anomaly that I found only
> happened with more exposure (when the density goes above 1.6). Those made
> with low exposure, the steps go proportionally.

It depends on what you mean by "more" and "low" exposure, but if you
expose film sufficiently long you will start losing density. The usual
s-shaped DlogE plots will show a down slope in density if exposure
continues past the maximum density point. It is a form of reciprocity
failure that occurs at high exposure levels.

Perhaps this is what you are seeing?

- Wayde
(wallen@boulder.nist.gov)