Circle Of Coverage At Small Apertures?

[David A. Goldfarb]

I know that's the modern engineer's view, but personally, I'd rather have a soft corner and a little extra flexibility in movement than a vignetted corner.

[Wellesley Browning]

Erik's fine (and finally, understandable!) explanation, it seems to me, implies that a data chart might be constructed which would compare a lens' light transmission both in the center and in the corner, as the aperture is reduced. This chart (or its implied graph) would illustrate the lessening edge falloff as the aperture shrinks.

Does this falloff approach zero as the diaphragm size also approaches zero?