so.... does a typical lens have a curved field of focus (constant length arcs from a single point at the center of the lens), or are they corrected to give a "flat field" of focus, where everyone 10' from the lens, as measured in coordinates, not radially, are in focus?
I thought it was the former, with only a few projector lenses or macro lenses corrected for the latter. Is this the case?
Geoff