It was observed that the luminance of the pupil is not proportional to the pupil area. For instance, the luminance of a 30 mm2 pupil was found to be only twice that of a 10 mm2 pupil.
Observations revealed that the brightness within the pupil does not correlate with its size. Specifically, the brightness in a 30 mm² pupil was found to be only double that of a 10 mm² pupil.