Quote Originally Posted by Tom1956 View Post
So which step in the Stouffers' wedge did you use that determined your film speed?
If you plan to use a Stouffer step wedge, then you change the procedure significantly and you open the door to better testing. A step wedge gives better tests than if you do camera tests exposing for Zone I. I personally contact a step wedge to light in a sensitometer, which is basically a box that aims a flash at the strip.

On your original plan of tests for Zone I, one of the sheets would have hopefully measured close to a density of 0.10 and the EI speed you shot that film at is what you would consider your tested speed.

When you use a Stouffer step wedge, depending on the one you buy, the difference between steps is 1/3 or 1/2 stop each. So hopefully, when you exposed a step wedge, one of the steps of your developed film measures close to density 0.10 - You can count the steps to arrive at how many f/stops of light are blocked (you can do that in your head)... Or you can do some math using the known density of that step to account for how much light was blocked by that step.