Bruce;

This is 1 roll of 120 film exposed at (from L to R top to bottom):

ISO 160 - reference, 25 - t, 50 - b, 100 - t, 200 - b, 400 - t, 800 b.

These were then contact printed onto Endura paper at 12" with one stop increments from f5.6 to f22. The film and paper were processed normally. Due to the changes in f stop, the paper should show at least one image that is "correct" or nearly correct for the ISO rating. The result shows that usable or even quite good pictures can be obtained from about ISO 50 to about ISO 400. And, no push is needed.

So, all of the sheets have the same ISO rating, just a different printing exposure to "highlight" the best frame with the "right" ISO for the amount of light given during printing. The bottom line is that negative films have a huge latitude without push or pull processing and usually look best about 1/3 stop overexposed.

PE