Jonathan Leavitt

When you focus on the center of a flat test pattern using a lens that has noticeable field curvature, the measured sharpness always tapers off from the center because it is going progressively out of focus towards the edges. You would need to re-focus the lens at various points from the center and somehow incorporate those results into the data. How can one do that? For example the attached Zeiss Biotar does not improve at the edges between F2 and F8. I assume this is field curvature, because stopping...