Quote Originally Posted by Mike Wilde View Post
When I am calbrating an unknow film (and I do this semi often - on found films in bulk loaders I buy, etc). I expose them to a reflective step wedge test target in a copy camera, to determine the minimum effective exposure to overcome base and get image content off of the toe of the H-D curve.

Then a transmission step wedge is useful.

I use the step wedge in a slide copier where the light source is daylight to fine tune developer times.

For reversal, thiocyanate into the first developer has always worked best for me to get rid of the overall grey haze.
Mike. Good advice. I'd never heard the term step wedge but, yes, I had been thinking of printing a zone system strip in the darkroom to use in order to a get a better calibration, especially as I also use a Weston meter. I guess this is the same as a reflective step wedge. But I wonder, can such a reflective 9 step wedge be bought cheaply in the UK? I now see that there is a nice looking thing called a Stouffer 9 step wedge but they do not seem to be available here.