I have the Q-13 step by Kodak, but it only has 20 steps. When trying to linearize my QTrip curve, it requires entering values in 21 boxes... it was a little tricky trying to get a reading from 20 steps to fit into 21 boxes, even with interpolation. Does the Stouffer contain a full 21 steps? It was hard to tell from looking at the graphic on their website.