This page shows dual sets of crops, each focused slightly differently. One series is front-focused for f/2, which means poor f/2 results in the nominal plane of focus, but combined with focus shift results in far superior results at f/2.8 and beyond. The other series shows ideal focus for f/2, which delays sharpness all the way to f/8.
By comparing these two series crops, even the skeptic can quickly see that focus shift is a thing, and that it can make a big difference in total sharpness. Photographers looking for optimal results should study these findings and follow the recommendations for mitigation.
Includes crops and commentary and mitigation strategy.